Hello Neil and thank you for asking the Disney Parks Moms Panel such an important question about your upcoming trip to the magic of Walt Disney World Resort.
I'm delighted to share that both you and your dear wife are sure to discover there are many wonderful and super helpful
Services for Guests with Disabilities including accessible Resort rooms which are detailed in this
Services for Guests with Disabilities at Disney Resort Hotels link. Your dear wife may even wish to consider having her particular needs noted onto your Resort booking by speaking to a helpful Cast Member by dialling the number contained within my previous link.
For Guest convenience when visiting the Disney Theme Parks there are
Services for Guests with Mobility Disabilities which contains a full list of accessible Attractions where Guests can remain in their wheelchair/ECV or must transfer from wheelchair/ECV or must transfer from ECV to a provided wheelchair. General assistance and safety guidance will of course be provided by helpful Cast Members when boarding an Attraction plus if necessary the use of a ramp or similar to aid the boarding process, however it's worth bearing in mind that Cast Members are not permitted to physically lift Guests when transferring onto Attractions.
I also thought you may find this useful
Guide for Guests with Disabilities - Magic Kingdom Park to be a great planning resource for your upcoming trip!
Have a great Disney day.
~ Jane