Well, we know that the Andalite homeworld has less water than Earth but otherwise is very similar. There's references to the 'wastelands' or 'badlands' or something along those lines, which leads me to believe that there is a distinctly large desert on the planet somewhere. I always assumed that the Andalite continents were a bit less broken up, a bit closer to a Pangea scenario, due to the larger land mass.
There may also be areas of swamp, which would probably be places the Andalites steered clear of (along with the deserts) due to the squishy ground (or lack of grass) that would make feeding difficult. Similarly, there's probably at least one major mountain range which may be the home to more 'wild' Andalites (hermits, anyone?).
No cities, but several major space docks that might as well be cities, except no one lives in them. They are simply there for the final collaboration of space craft and other major projects.
I always saw the Andalite world (which, btw, I have a friend who figured out should technically be called Andal. Duh! I had never thought of that before) as extremely similar to earth. It has three suns? Or is it three moons? Or am I mixing it up with the Pemalite world? Gah. Anyhoo, the sky is more red than earth and the air is probably a bit different, but not much. For some reason I always thought that the Andalite planet was the fourth planet from their sun. Not sure why, lol.
