You can get additional travel destinations by getting Tamatomo stamps, obtained after getting all happy items for a character.
4 stamps - Henshin Jo
8 stamps - Patchi Onsen
12 stamps - Melody Land
16 stamps - Concert
20 stamps - Waru Cafe
24 stamps - Uranai no Yakata (fortune telling)
28 stamps - Gotchi School
32 stamps - Gotchi King's Castle
More destinations can be downloaded, as well.