Macalania Forest. It's just such a magical place, and you can feel the magic int eh air. The music is perfect and I love how the place looks. Allt he blue trees and iceicles, all the glowing lights and the atmosphere that just makes you feel so small.
Guadosalam, Besaid, Mt. Gagazet, and if you could actually explore Bevelle, then it would probably be my favorite