Islands.
Really, we need more islands in the Pokemon games. Like, some connected with bridges, and some that you need surf to get to?
Also, not every island needs to have a town, but how about every island has different Pokemon to catch?
You can have volcaninc islands with Fire and Ground types, then some tropical ones with grass and bug types, then some big caves on a couple of island that can have even more Pokemon types to find.
You could also add some underwater caves where you can catch some water types that aren't accessible on the surface.
And on the "mainland" you have big cities with lots of shops, Gyms, and on some islands with villages and/or tribes, they use some healing experts instead of Pokemon Centres!
There would also be some big islands with Gyms on them, like some exotic type of islands.
I know there isn't really a real life place like this, or maybe you could take Indonesia for example for it's wide variety of islands, or some other country.
I just had an idea, y'know? 