Hi Jen ~
It is really nice of you to plan ahead. Disney World is a great place for
Guests with Disabilities. They try to meet as many Guests' needs as possible including those with
mobility disabilities. By clicking on the link provided, you can see the attractions that allow Guests to remain in their wheelchairs or ECVs, those that require Guests in ECVs to transfer to wheelchairs to board and those that require Guests to be mobile to enjoy.
If the wheelchair user in your party must pivot to transfer, I think it will be difficult for her to transfer to most of the attractions listed under the section showing "Must Transfer from Wheelchair/ECV". Splash Mountain, Haunted Mansion, Prince Charming Regal Carrousel, Tomorrowland Speedway, Astro Orbiter, Space Mountain, Pirates of the Caribbean, Seven Dwarfs Mine Train, Maelstrom, Kali River Rapids, Primeval Whirl, Expedition Everest, Mission: SPACE, Test Track, Spaceship Earth, Rock 'n' Roller Coaster, and Tower of Terror may be very difficult because of the design of the attraction vehicles. Most you have to step down in (i.e. boats) or over a threshold to get in the attraction. Soarin' may be possible if she can lift up a few inches in addition to pivoting during the transfer. AllEars.net has an attraction photo gallery of attraction vehicles if you would like to get a better idea of what she would be attempting.
Keep in mind that you or someone in your party will have to assist her as Cast Members are not allow to physically assist Guests when loading and unloading attractions.
I am limited in space but please feel free to visit again with all of your questions. It is a pleasure to assist you!
Wishing you minnie magical memories :-) Allison V.