In Magic Kingdom, they have a Toontown Fair area. If you go into the "tent" looking building between Minnie and Mickey's house you will see an area to the right marked "Mickey & Friends", "Pooh & Friends" and "Disney Princesses." We were just there in September and saw Cinderella, Aurora, and Snow White.
You can also sometimes see them in MGM. We saw them near the big hat in MGM in February but only Mickey, Tigger, and Stitch were there in September.
Have fun! The line in Toontown Fair was long but it was so worth it! My daughter looked at Snow White like she was truely royalty!