I would let her watch any movies that have rides/shows associated with them (if you plan on riding them). Especially the rides that have story lines in them, so that she will recognize familiar scenes.
For example:
1. Peter Pan
2. Snow White (avoid this ride if she scares easily)
3. The little mermaid if you are going to the show.
4. Lilo and Stitch
5. Winnie the Pooh and the Blustery Day
6. Lion King
7. Beauty and the Beast
8. Finding Nemo
Of course, she may be too young for the Pirates movies and Haunted Mansion, but those rides were around before the movie and I loved them at six.