Where does a traveler arrive when a planar location's unspecified?

Question

When a creature is successfully targeted by an effect that transports the creature to another plane but no location on that plane is specified, where does the creature arrive?

If the plane is the Seven Mounting Heavens of Celestia creatures "always find themselves in the surf of an ocean surrounding Mount Celestia" (MP 133), but does a canonical Dungeons and Dragons 3.5 list of these--let's call them--arrival points exist? A homebrewed, third party, or other edition's arrival points list is awesome, too, if a canonical 3.5 one's unavialable or, in your opinion, terrible.

When an effect causes transportation from the Prime Material Plane to a coexistent plane (e.g. the Ethereal Plane, the Plane of Shadow), I assume the arrival point is the equivalent point on the coexistent plane that target creature occupied on the Prime Material Plane, but I'd enjoy this bold assumption disproved.

If the creature is transported at random to another plane (e.g. the spell reality maelstrom [evoc] (SpC 168-9), the supernatural ability portalwake of the teratomorph (MM2 194)), the chart Random Planar Destinations (SpC 169) leaves the "layer and exact location on the particular plane... up to the DM," but that's less than helpful to the DM of a PC who has little information about--but nonetheless wants to travel--the planes.

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Background
While considering this question I was again disturbed by the vagueness of the spell plane shift [conj] (PH 262), which says...

You move yourself or some other creature to another plane of existence or alternate dimension. If several willing persons link hands in a circle, as many as eight can be affected by the plane shift at the same time. Precise accuracy as to a particular arrival location on the intended plane is nigh impossible. From the Material Plane, you can reach any other plane, though you appear 5 to 500 miles (5d%) from your intended destination.

The the Dungeon Master's Guide adds that the spell plane shift "deposits the spellcaster on the first layer of the plane" (151), but it's silent about where on that plane, and some of those planes are infinite.

My House Rules
In the spells plane shift and teleport [conj] (PH 292-3) et. al. the destination is generally where the creature wants to arrive, while a location is the the most obvious or common entrance to a named site. In my games prior to using a general teleportation effect like teleport or plane shift a destination must be designated as either a location, layout, or object. (Exempted are specific teleportation effect like citygate [trans] (Dragon Compendium Volume 1 62), door to great evil [conj] ("Ghostwalk Web Enhancement" 6), and gemjump [conj] (SpC 101).) If your house rules define destination and location differently, that's cool, but try to answer with mine in mind.

Answer 1

To answer the question rules-as-written:

Wherever the DM thinks appropriate. There appears to be no answer beyond that (especially nothing as specific as a table of default destinations) using official 3.5e materials - 3PP d20 material or earlier editions may be another matter.

For a more useful answer, we need to go beyond rules-as-written (which after all is the whole point of having a DM in the first place.) The best answer therefore depends on the style of game being played, of which there's infinite variation but here's a few ideas:

The narrative answer:

Wherever adds a good story twist, which probably means a populated area with NPCs to interact with. If it's the PCs first visit to that plane, a large city would probably be a good way to introduce them to the plane, as well as providing a useful home base. On the other hand, a small settlement would provide for more intimate interaction with local NPCs and lead to easier story hooks.

The conjectural cosmological physics answer:

The 3.5e Planar Handbook (p151) mentions planar breaches between planes, where the dividing line between two planes has worn thin. It follows that this would be a likely entry point to another plane, as the barrier between the two would provide the least resistance at these points. Planar material could be flowing in or out of this breach depending on the relative density of the planes concerned.

The Hollywood movie answer:

As mentioned in the opening question, there may well be a specific location on the destination plane that is related somehow to the point of origin of the travelers. Travelers from the plane of water may arrive in the middle of a lake or ocean, for example, while those coming from the plane of fire may arrive in a volcanic area.

To the best of my knowledge, there's no definitive list of these, and in many cases it's necessary to tweak the idea to something that would be appropriate on the destination plane - arrival from Mechanus may seem difficult to do if the destination doesn't have clockwork, but a ring of standing stones shaped like cogs feels like a good fit.

The random chance answer:

The DM grabs whatever maps or charts they have of the destination plane (sketching something out if necessary), makes up a grid reference scheme if needed, and rolls dice. Having a few easily adaptable generic maps at hand (with some locations that can easily be tailored to any plane) can be useful here. Tables would work equally well if preferred.

The murderhobo answer:

The PCs arrive at the entrance to the lair of planar monsters that need to be killed, because... they're not currently dead enough, and they have valuable stuff to take.

The "Teach them a lesson"/"My players are masochists" answer:

(Thanks to Zachiel for - unintentionally - reminding me to include this)

They arrive in the worst possible location. Covered in flames on the Plane of Fire, drowning on the Plane of Water, inside solid rock on the Plane of Earth, between two rotating cogs on Mechanus, five thousand feet above one of Arcadia's layers, etc. You'll probably never run into the problem of unspecified destinations ever again...

Answer 2

There is no RAW list, and there cannot be.

As written, Plane Shift is supposed to be extremely inaccurate and random. The important part is:

you appear 5 to 500 miles (5d%) from your intended destination

This means that no, there is absolutely no way to be less than 5 miles away from your intended destination, and so there cannot be a RAW list of spots where you arrive. Even if you Plane Shift while aiming for "the Ocean surrounding Mount Celestia", you would arrive 5 to 500 miles from it (some travelers use this, and aim for a destination several hundred miles from their actual destination. It works, sometimes).

As for totally random travel, without a planned destination, it is RAW up to the DM. The characters can appear anywhere on the plane, and so having a list of where they appear would defeat that. Without a destination, it is technically possible for characters to arrive at a distance of a billion universes from the nearest city. Have fun.

There are an unofficial undefined lists

Planes are infinite, which is pretty big (I could go onto the ramifications of them being infinite, but that would be a bit off-topic). And as impressive as GM can be, infinite is a bit too big to handle.

Therefore, most DMs playing in a planar setting tend to have their personal list of where characters are most likely to appear (usually the biggest city of the plane, or one of its most representative elements).

This is partially supported by the setting if not by the rules. Most Planes, even though supposed to be infinite, are described are pretty finite (there seems to be at most two or three cities per Plane). These allow the DM to more easily pick up a destination when the PCs are travelling without a destination.

Answer 3

There's no hard and fast rule, but in lieu of anything else, you could simply choose a random point of interest on that plane as the target, under the assumption that frequently used teleport targets could have a form of resonance that naturally attracts directionless teleportation effects, and then do the 5-500 mile roll from that. Following the point of least resistance, as it were.