Noting the disparity between the much more diverse world map and it's in-game counterpart (Thanalan to Shroud scenery transition of 2 ft, etc), I became curious as to what environments you'd like to see in the game.
I just have a couple guidelines:
1. Let it have a place in the actual world map.
http://ffxivmaps.com/img/world-map-official-large.jpg
2. See if you can make some backstory to it, and try to connect it to some extent with nearby plots.