I'm planning to run a Planescape game in 3.5 and want to offer players the opportunity to play unusual characters within the system. Ideally power level wouldn't be a concern, but some players might prefer to play more standard races and I don't want character level skewed across the party. Any suggestions or concepts would be very helpful.
- Give everyone a free level adjustment of +1 to +3. If they want to play a standard race, they can have an equivalent number of levels in their racial paragon class.
- Apply templates to the core races to raise their level adjustment. For example, all elves from a certain plane have the half-celestial template. Or, just allow PCs free level adjustment to buy the template of their choice.
- Use the Pathfinder rules for monsters as PCs.
- Use E6 rules where level adjustment costs a penalty to ability score point-buy instead of level. A race with no level adjustment has 32 point buy, LA +1 has 25, LA +2 has 18, LA +3 has 10, and a LA +4 race has 0 point buy, all ability scores starting at 8 before racial bonuses. (Thanks KRyan for identifying the rules.)
- Use Savage Species style level adjustment progressions. These divide the race into one-level chunks so that you can play them at lower level and gradually progress to the full race or template. For example, half-dragon is normally ECL+3, but with a half-dragon template progression you can take the half-dragon properties one level at a time.
Class Abilities almost always overshadow Racial Abilities at later levels
Except in the case of fairly weak classes, most classes tend to overshadow any racial abilities a character has at later levels. Usually, this ends up meaning that the character who picked the race with a level adjustment ends up far weaker at later levels than the character who picked a normal, no level adjustment race.
Consider the Level Adjustment Buyoff from Unearthed Arcana
Obviously, this isn't ideal for keeping the party level even at first, but buying off level adjustment through a fixed XP cost is much more likely to keep the party level even across all members later in the game. If your game doesn't use XP (say, you advance characters at the speed of plot) then consider giving a level adjusted character extra levels at certain points until their level is equal to that of the party. Say, a level adjusted character hits level 3 when his allies are at level 4, give him an extra level to bump him up to four. You could potentially use the Level Adjustment Buyoff table as a guideline for when you grant characters their "catch-up" levels.
Give the Characters with Level-Adjusted Races their Racial benefits over Time
Instead of the Level Adjustment Buyoff I mentioned above, you could instead parcel out racial abilities and stat boosts as the characters level up for the various level adjusted races, and make a weakened version of the race on par with normal races for the early levels. When you grant the characters with Level Adjusted races their racial benefits at later levels, they'll be a nice reward but still shouldn't overpower the more ordinary characters. The only downside I can see to this particular method is that it requires a little work from you to decide when to give each character their individual racial benefits. Hopefully either of these will work for you.
One model I was looking at was offering 40 points in point buy (it's a higher-powered game) and allowing players to trade 2 points for +1 in free level adjustment, to a cap of +5 LA. For characters with no level adjustment and no template additions, I'd also throw in a bonus feat.
First I think power level is a concept that the GM decides because he sets the tone to the worlds and is also responsible for creating the encounters thus he needs to adjust the power of his players to A: survive the encounter if possible, B: not blow through each encounter with no effort or risk by the players and C: create a sense of realism that can fool them to believe that they are struggling in the world to become heroes not just hacking the game and winning everything.
Now to address your question; If you give your players a list of good templates that are well balanced but a large list from +1 LA all the way to +3 LA you will have a large variety to your base races that can match almost any other starting creature from the SAVAGE Species book; also if you give the players the chance to play awakened animals it can also bring balance to your other race options.
It will vastly depend on what everyone is playing on a good balance of level adjust and power to the rest of the party; If one player is play say a Solar and another player plays a Half-Elf you beginning power balance is off by a lot. Even a Solar by level will still be much more powerful then your base class Half-Elf.
It will all depend on what everyone wants to play.
Now for your other part of the question how can you keep everyone's level around the same if all the power balance is hugely out of balance the answer is easy Simply remove the Level Adjust from all the more powerful players and you will all level at the same rate. This will make the more powerful players even much more powerful then the standard races and might change your game quite a bit.
Answer A: remove LA from all templates and race choices to equalize experience gain.
Answer B: give all standard races a template with level adjust that equals out to the highest LA from any other race choice.
Answer C: count the party as a single character with a single LA adjustment from the highest LA among the party and give everyone the same amount of exp as the player with the Highest LA in the party.