Wow! Great energy Pittypat! To the OP, we took my mid-60's parents (also basically in good health) last March and they loved it (going back this year). However, after about Day 3,we did discover that they aren't as young as they used to be. My mom had a
scooter (planned and delivered at the beginning of the trip because of her recent knee surgery), so she was always ahead of those of us who were walking. However, my dad (who is the big walker) tired by mid-day and the return to he hotel for a a break after lunch was welcomed! By about the 4th day, I switched the schedule around so that we could sleep in/relax and, a few times, we would head out to the parks ahead of him so that he didn't have to try to keep up with our walking pace. When we went to AK, we planned to be there the entire day (with no return to the hotel break), so we rented him a park scooter...which was a nice break for him. I was suprised he was willing to do this, but so many others were using them and he saw how much easier things were for my mom.
Little things seemed to come up, that I just didn't notice....like it was easier to walk along the river from Beach Club to Epcot instead of on the main walkway because it was flatter, etc.
All in all, it was a great trip and, it was my dad, who hinted about coming with us this year (which we think it great!). They loved the restaurants (especially the sugar free desserts that we specially requested- no extra charge).
My dad also liked the Walt Disney walk through exhibit at MGM and, of course, some of the older rides that he remembers taking me on when I was young (in the 70's).
They seemed the most politely clueless with things like Playhouse Disney Live and the High School Musical Pep Rally. They don't live near us, so they really aren't up on pop culture for young children. However, they had fun watching my dd's have fun!