Don't limit yourself to just animated Disney features, Pirates and Tron were in KH2 after all! I would like to see a Mighty Ducks world, only for the cheese of it. I doubt it would actually be that good. It would also be cool to see a world based on the latest Disney feature, Tangled.
Oh! And Mary Poppins might actually be a fun world to visit as well. I think the interactions there would fit into the KH story nicely.
And of course, Pixar worlds would be awesome, like Toy Story or Monsters Inc.