I could just be biased, as Final Fantasy X was my first in the series (far from my favorite, but it still counts for something), I always felt that the tropical, water based setting was my favorite. It wasn't just the geology either, I liked the interior designs of buildings and the like. The closest I think I've been to finding a game that reminds me of FFX would be Chrono Cross (where the title screen is literally underwater, and I think it uses the same boot up noise when you press start too).
Anyway, discuss the Environment of Spira, and how awesome _or lame you think it is.