We've done Disney twice now with him renting wheelchairs just at the parks and that seems to work the best. There are times when being on his feet is best, whether needing to stretch his legs or if we have to run for a connection. He's in good enough shape, and I think would feel bad taking the facilities meant for someone truly disabled when he isn't. The electric wheelchairs are pretty slow, also and I like the exercise of pushing him around.
Thanks for your concern though!