I go with my friend who is 67, and I am 47. I am the one in poor health though. I have to go at an easier pace. I think there are a lot of rides that they may like to do. My friend gets motion sickness and I have neck issues, so we don't ride the thrill rides, but we did do many rides together. She even did mine train and test track with me, even though they may not be able to do those, don't automatically rule out rides. There are plenty of calmer ones. I don't know if you're involving them in the planning or not, but you (and possibly they) can always look up some videos of the attractions and view them and see what appeals. If it isn't a surprise I would get them in on the planning. Rides like Haunted Mansion, Peter Pan, Pirates, Soarin', Jungle Cruise, The Safari.... And many more are on our not to be missed list.
You may want to look at the seniors touring plans and the adult easy wdw cheat sheets, especially you don't involve them in the planning. These will list a lots of the must see attractions. Since I need to take it slow and have other medical issues, I always schedule at least one table service, if not two, per day. Gets me off my feet for a good break.
l hope you guys have a wonderful time.