I am over 50! I like all things Disney except waiting while standing. I just can't stand in the same spot for more than 5 minutes. If the line keeps moving, I'm fine. I also absolutely cannot sit on the ground. So that pretty much cuts out waiting for parades, fireworks, characters, or any ride with more than a 15 minute wait. I like the smooth coaster rides, but no longer enjoy Space Mountain. I also can't do Tea Cups.
I love the shows if I can sit down to wait for them. Sometimes that means arriving early to snag one of the few seats in the show lobby (American Adventure, muppets, country bears, France movie). I really don't mind waiting as long as I'm seated (Fantasmic, Beauty and the Beast). I also like just sitting on a bench and people watching while you do something else so don't feel like you are abandoning me. The hour I sat in a rocking chair overlooking the river while you waited for Big Thunder Mountain was delightful!
I like looking through the gift shops. I walk around them slowly looking at everything, but I almost never buy anything. This drives some of my relatives crazy. They see no point. I also like visiting other resorts for a drink, or just a cup of coffee. A Disney trip is no longer just about the rides. I like to board the Friendship cruise at Epcot and take it all the way to Hollybwood Studios, stopping and visiting the Boardwalk, Beach/yacht Clubs, and Swan/Dolphin along the way. I also love doing my version on the Monorail crawl. Use the monorail to visit the Contmporary, Grand Floridian, and Poly resorts for a sort of progressive dinner at the three different food courts.
Since I turned 40, I became an early riser, so I can easily make rope drop. Unfortunately, I also snore now, so if we are sharing a room, I'm sorry. That also means that by 10 pm, it's lights out for me. After 6-8 hours in a theme park, I'm done. No more commando for me, but I don't mind if you want to stay.
OP......I hope you have a great trip with your Mom. If she has never traveled before, she may experience some fears and concerns about being away from home. She may feel anxious, even while enjoying the trip and the time with you. If that happens, don't think it's because she doesn't appreciate the trip or the planning you have done. She also may need down time alone so it's okay for her to spend the afternoon alone at the resort, while you stay at the park. Sounds like she might be facing a lot of "first times" on this trip and that can be overwhelming. She also can't anticipate how she will react to the crowds, the waiting, the heat, the noise, the different foods. I hope you are understanding.
One last idea. If during the trip your Mom seems to be struggling a bit, consider renting a wheelchair. Not only does it provide a built in place to sit, but it also relieves her of some decision making since you are guiding her. And at $14 a day, it's a bargain!