I'll put this into 3 as I haven't played all that much RPG's, and some I don't care for at all. All belong to FF.

1. Spira (FFX) - Final Fantasies most magical world. I'm slightly biased as well because I love the music in this game, and when I hear it's music I think of the area.

2. World (FFVIII) - It's so otherworldly yet so peacful in places like Balamb & it's Garden, Dollet, & Deling City.

3. Ivalice (FFXII) - Place was just beautiful.