I'm going to ramble for a bit

and you can extract any info that may help you on your trip--- my circumstances were different.
I went to WDW 3 times over 18 months as a traveling companion to an 85/86 yo lady w/ mobility issues (broken hip) and mild to moderate dementia. Her son is a friend and he needed same sex help with mom. My input in planning, etc was somewhat minimal and that's OK!
Because of Miss M's loss of short term memory, getting her up, dressed, and out the door (on an
ECV that she had never driven) was a good hour or more; then to the food court and another 30-45 min for breakfast, then wait for bus and enter park- another 30-45 min. So you can see that by the time we got *into* a park, she had already been up for 2-3 hours.
[Just my opinion - I think it would have been preferable for someone to go get breakfast and bring it to the room, bypassing the schlepp to the food court and the change in surroundings for her.]
So we would arrive at a park about 10 a.m. By 3 p.m. she would start "sundowning" and by 4 she was pretty done in. Back at the resort by 5 and she was too spent to focus to eat.
An Epcot resort would have been a good option, but it was not affordable. I do think that if we had taken her back for a midday rest, we could not have gotten her out and about again. We sorta tried on Trip #2 for her to see Illuminations, but she didn't want to go and I don't think she would have gotten much out of it except more fatigue.
While the ECV was a good option--it was not a great option in HER case. She had never driven a car. The ECV required a lot of concentration on her part and she made a lot of mistakes, most of them harmless to herself and others. The most memorable was semi climbing the walls at the Country Bear Jamboree....
[Just my opinion - after the first trip I REALLY wanted a push wheelchair.]
The third trip her son discovered HE could pilot the chair while walking alongside. This was easier on both her sanity and mine.
She enjoyed all of the shows and LOVED Beauty and The Beast. American Idol also ranked high. Country Bears was rather lost on her and she found the Tiki Room "weird" LOL!
Other than FotLK, AK was pretty much a loss for her. MK was "too much." And while DHS is my least favorite park--it was her favorite
Again, everyone is in a different situation so certainly YMMV!