First of all, if you follow the link in my signature to the disABILITIES Board, you will find a lot of information about renting wheelchairs/
ecvs (in a FAQs thread) and look around the board for information about Guest Assistance Cards.
One of the problems for people who want a place to sit and wait is that there are almost no rides that actually have places to sit and wait once you are in line. Most of the lines are constructed so that it is not easy to see the rest of your party once they get to the entrance. And to prevent people from just going ahead in line, there is often not a way to get to the front of the line easily without going thru the line. Some of the shows have a large room for the waiting area for the preshow. Most of those have a few benches, but they are first come, so if someone is already sitting there when you arrive, you are out of luck.
So, for someone with what WDW calls "Endurance Problems" (difficulty walking distances or standing), the CMs usually recommend renting an
ecv or wheelchair. That is really a common sense solution when you consider that the average attraction does not have any place to sit and wait and the average guest to WDW walks between 3 and 9 miles per day (most of it going from attraction to attraction, not standing in line.) Many of the lines are a long distance to walk (even in the Fastpass line - Three I can think of offhand are Bug's Life and the Safari in AK and the Pirate ride in MK).
If he doesn't want any special treatment, it might be helpful for him to know that all of the Fastpass lines and most of the regular lines
are wheelchair accessible and most are ecv accessible. He will probably feel more strange about getting special treatment with a Guest Assistance Card than he would just going thru the regular lines with a wheelchair or ecv.
Another way to avoid standing in line is to use Fastpass. depending on exactly when you are going, you may find that the lines are not really that long (at certain times of the day, quite a few lines are walk right on).
My FIL finally rented an ecv for the first time on the last day of our trip last March (after "thinking" about it for many, many years). At the end of the day, he said it was the first time in years that he had ended his day at Epcot without pain. He also said he realized how much he had missed over the years, how foolish he felt for not getting one years ago. If someone uses an ecv, he may not
need to take every other day as a rest day because he will not be expending so much energy at just getting around.
One little substitution has helped some posters to the disABILITIES Board with looking at ecvs/wheelchairs in a different way.Think of glasses - people use them because they have difficulty seeing without them. Most people would not try to avoid using glasses if they need them or put off using them until they absolutely could not manage without them. Everyone understands that glasses are a tool that help if you have vision difficulties. If you need glasses and you choose not to wear them, your eyes will get tired faster and you will probably end the day with a headache.
For someone with endurance problems, a wheelchair or ecv is the same sort of tool for a different part of the body.