I was just musing on Spelljammer with a folks in my gaming group. It gives me the idea that we could make the "world" a kind of interdiemensional network of connected worlds. No need for everything to connect geographicaly if we agree to use some kind of portal to jump to other worlds. The idea of Crystal Spheres and Spelljamming not required.

This would allow for wide variation in styles and map content as well as keep everything usable as one large setting.