I really liked some of the answers given to the question about enhancing skill challenges particularly the ones related to making it more role-playing based.
So, now the question is, when you get to that point, how do you get all the players to participate in the skill challenge without breaking the immersion by simply going around the room asking them what they do?
My first method is group checks. The traditional example is a difficult bit of travel: if you're going through a desert, maybe you call for a group Endurance check, or if you're climbing a cliff, maybe you call for a group Athletics check. In skill challenges, group checks require half the group or more to succeed, so for a five person group three of them would need to succeed.
If you do this, I recommend setting the difficulty level of the check at easy by default, because some characters aren't going to be trained in whatever skill you're using. That doesn't mean you can't use harder difficulty levels, of course -- just think about it carefully.
A lot of published skill challenges try to make this work in a diplomatic setting. E.g., the King says he wants to hear arguments from everyone before he'll agree to whatever it is that needs doing, or the madcap faeries want everyone to entertain them. In my experience, these often wind up feeling artificial. If you want to do something like that, foreshadow it rather than just dropping the group requirement on the players out of the blue. Perhaps people mention that the King tends to be concerned with the kingdom as a whole, not just individuals.
My second trick is specific skills. You can identify key skills that only the quieter characters have, and make a skill challenge that calls for those skills. This works better if it's always specific players who aren't participating, of course. I'm usually willing to drop some hints here, or even just call for a character to roll. For example, say there's some nature-oriented skill challenge going on, and the quiet guy has Nature, but he isn't coming up with any ideas. I'll just ask him for a Nature roll and if he succeeds, I'll feed him some information.
That works much better for knowledge-oriented tasks, since that way you're just telling the character what he knows rather than trying to dictate his actions. On the other hand, you can turn almost anything into a knowledge-oriented task. "Hey, Bob, roll Streetwise... OK! You've always been in tune with the streets, and while everyone else has been running around you've noticed there're a lot of thugs drinking at that White Heron bar over there."
You can make that kind of forced roll give a +2 to future skill checks rather than counting as a success or a failure, btw; that also reduces the feel of railroading. You're not walking them through the skill challenge, you're making sure they're able to apply their knowledge well.
My third method is splitting the party. If there's a good reason for the party to split up, the guy who always does all the Athletics checks might not be there when he's needed. A sneaky little variation of this that I've always wanted to try: capture the party spotlight guy -- you know the one, the guy who's always up front and pushing the ideas and so on -- and let the others do a skill challenge to break him out. The focus of the game is on him, which should satisfy that urge, but everyone else gets to be the active participants.
Finally, as always, talk to the players. I don't like to kill the flow of the game by over-analysis during play, but I find it's useful to chat a bit afterwards when I'm working on something like this. It's always possible the players are looking for something in skill challenges that you aren't giving them, and if there's one person holding down most of the spotlight, maybe he doesn't realize it.
You could encourage this by providing a challenge where a host of different skills can help out, but no skill can be used more than (say) twice. Characters won't be trained in everything...if the challenge is going to succeed, everyone can chip in by using the skills they are good at.
To make sure you get this right, you should know your characters strengths, and tailor the challenge to fit...especially towards the characters that are least likely to speak up on their own.
But here's the trick: if you don't necessarily tell them all the skills they can use, and you set a precident of having them justify using a particular skill to you (even if you already agree!) they'll think about it and/or role play it out. Let them convince you through their character's words/actions that it makes sense. It will provide them a sense of immersion as they describe why what they're doing should work.
Another method is to make everyone have to succeed at some kind of skill challenge for them to get past a particular difficulty. Perhaps a sphynx wants wisdom from each of them before it will let them by. Each player can decide what they want to relate to the sphynx, based on what they are skilled in, but the sphynx is easily bored; he doesn't want to hear about the same topic twice. The players can fail, succeed, or perhaps even impress the sphynx with their range of knowledge, maybe earning a special bonus.
Getting players to volunteer ideas and information without just asking for it is another matter. One way you could encourage that is by having some kind of indication that (real) time is of the essence.
For example, when they encounter the sphynx, and he bellows at the first character that he wants to be impressed, you (the DM) flip an hourglass, and tap your fingers impatiently, and lick your lips. The player/character will rapidly get the point that they have to react quickly, and volunteer something (or something bad will presumably happen). If you start with a bold character, they'll get idea, and do something. Then, having this example to follow, other players can follow suit as the sphynx accosts them in turn.
You have to have a firm image in your mind of the challenge, and how that would be addressed by various skills. Then you have to convey that image to the players.
Describe that combination magical and mechanical trap to the players extensively. Be sure to mention the heavy lever that someone will have to use Athletics to lift.
What I'm getting at is that you should have a complex challenge with multiple, different, specific challenges. You should play your challenges for requiring the different characters. Make clear that this will require everyone's attention to complete by describing the different parts that apply to different characters.
If there's not something for a player's character to do, they won't be involved.
As written, the default skill challenge system kinda expects everyone to participate. The Dungeon Master's Guide 2 has some great advice about running skill challenges, and you should definitely check that out. For example, you can ask everyone to make a Stealth roll and require half (or even all) of the group to make it to grant the success.
The Obsidian skill challenge system (PDF) by Stalker0 lays out a set of alternate skill challenge rules that make it easier to role-play. It also encourages players to take part in a skill challenge even if their skills aren't the best for this particular problem.
Players like to roll dice. They want to participate in a challenge, be it combat or role-playing or a skill challenge. However, the core rules present a system that punishes the entire group when an individual fails. The Obsidian system rewards a group when the individual succeeds. It's a subtle difference, but an important one.
In the traditional system, every player must participate and the group must earn a number of successes before getting three failures. Every time a player rolls the dice, it's a chance to push the group one step closer to three failures. Worse, to figure out how to participate without failing, players often stretch the limits of believability by shoehorning skills into weird uses: "I use Athletics to show off my climbing ability to impress the Duke!" No way.
In the Obsidian system, players do not have to participate, but if they do, their failures do not hurt the group. The group has three "segments" to achieve a certain number of successes. Falling short of that goal might mean a partial success or just failure. Each player gets three opportunities to make a skill check or use some ability that helps, but the skill really has to apply to the situation.
Why does this help keep immersion? Mainly because players are not stretching their skills in mind-breaking ways. Also, it's okay to skip a player. You don't have to circumnavigate the table, either, asking each player what they're doing. Just let them fire off ideas and role-play, and then ask them for skill checks at the appropriate time (see my suggestions for this in the other skill challenge thread).
If a player who has already gone "in this segment" wants to go again, you can handle it one of two ways:
In general, I don't find it immersion-breaking to ask a player, "What are you doing?" Your mileage may vary, though. What kicks me out of flow is the hemming and hawing about game stats. Don't let players do this. Push them back into character: "No, what is Throndar the Cleric doing?" Role-play. Get them to describe their character's actions. Avoid talk about skills. The only contact with the system that has to get in the way here is "Roll Religion" and then "16" and then you're back in the flow, describing stuff from the viewpoint of the character.
Be a proactive DM.
You can start by imposing situations on PCs. Just point to a random PC (roll a dice or something) and say here's something happening to your character" and then allow the player to come up with an idea to deal with the situation. This could be a skill check but it doesn't have to be a skill check.
But you should also allow for player creativity. So you might even suggest a skill to use: "Your character is walking through the crowded, bustling marketplace and suddenly gets bumped by a crowd of workers and street-urchins. You realize you've been pickpocketed.. But whoever did it can't be far off.."
At that point you could suggest an insight or perception check, (perhaps to figure out who stole the item) but if the PC says something like "Wait- I had my own arcane mark on my coin purse.. I want to use Arcana to detect it by magic..." you should allow it. Maybe bump the DC up +2, but definitely allow it.
But the point is: DMs set the scene and situation and then get the players to react. Don't put the burden of having the player imagine everything, (both the situation and resolution) because it's pointless. They'lll just pick their highest skill, make up an excuse, and roll it. The whole point of roleplaying is a 2-way interaction.
Also, try and develop improvisational skill at making failure interesting.
Good example:
DM: "You seem to have found yourself lost in the forest.. it might take some backtracking or a higher vantage point to orient yourself." PC: "Can I just roll nature?" DM: "Are you trying to backtrack? Describe what you are doing.. " PC: "Ok, well we crossed a stream during that last check, I'll try and get us back to there and realign our map.." DM:" ok, now roll nature.." (PC rolls, let's say they fail..) DM: You try and backtrack, but you are slightly off.. (that's one failure, by the way..) But now you have reached a muddy area with strange tubular mounds. Ranger PC? You recognize these as kruthik mounds. You guys are probably on top of or very close to a whole nest.. "
Bad Example: "You seem to have found yourself lost in the forest.." PC: "I roll my highest skill to escape. Uh.. Endurance. I'm enduring my way out. I got a 31."
Don't let the PCs pick the skill outright, especially not before you have defined the situation ina way that players can key off of. Pick the situation, suggest a skill, and be open to alternate suggestions if they are good ones. But the key is the interaction.
If the PC in the second example says "I want to use endurance.. I say we push forward, even if we're lost. " I'd probably improvise with something that needs to be endured, like a rainstorm or a sudden temperature change. And then make everyone make endurance checks..failed endurance checks might mean.."frostbite" or "randomly determined PC comes down with a hacking cough. You'll need to make shelter for the night.. "
And then follow that up with more roleplaying- maybe a nature check to gather supplies for camp, etc.
Keep the interaction rolling.
