Yesh! You should try it. It was actually surprisingly easy to paint canvas shoes. I'm very tempted to doctor my solid-colored real Toms, even.
Hm...let's see: for Epcot, you could do the Mickey head flags at world showcase (though this could be tedious and you'd need lots of different paint colors. Or you could go basic and do Spaceship Earth
For AK, you could do the obvious animal print. That'd be really easy to paint on shoes, too!
For DHS, maybe the sorcerer's hat on one shoe and a silhouette of Sorcerer Mickey on the other?
For MK, maybe the silhouette of the Castle? You could get a pair of sparkly pink canvas shoes and do this design and it'd be so adorable!
I wish I had a talent for sketching as I think it would be cute to execute these ideas!