William, I think you have a number of excellent options for making the trip magical for your little girl. I have focused my answer on the characters that you highlighted, but each park has several great options for small children.
Magic Kingdom is often a favorite for the pre-school crowd, with a large number of attractions that cater to little ones. Here, your Tinkerbell-fan can experience the new
Fairies Meet & Greet at Pixie Hollow, ride Peter Pan's Flight and see Wishes, the nighttime spectacular where Tinkerbell makes her famous descent from the Castle. At Disney's Hollywood Studios, you can see
Playhouse Disney-Live on Stage! where The Little Einsteins, and many other Playhouse friends entertain the crowd in a show where the audience is encouraged to get up and dance along. You can also make an Advanced Dining Reservation for Playhouse Disney's Play n' Dine, where your daughter can have breakfast with some of the Little Einsteins and other characters. Epcot has
The Seas with Nemo & Friends Ride, where you board a "clamobile" and can see Nemo and his friends among real marine life. Finally, at Animal Kingdom, you and your daughter can catch
Finding Nemo- The Musical. I recently saw this Broadway-quality production with my family and my kids loved it.
I hope you and your daughter have as much fun experiencing some of these attractions as I did writing about them!