What's really sad to me is the attitude that most of you have on this thread--which is that you're entitled to a seat no matter what, they deserve to stand, who cares about anyone else?, and generally that you're more worried about sitting for 15 minutes instead of making someone else's day. What happened to just being nice? I totally believe in karma, and there may be a day when I can't stand for 15 minutes after a day of walking around, or it hurts me greatly to do so. So, why wouldn't I now, when I can stand for that period of time without any harm to myself, offer my seat to someone older than me, or someone with a small child?
I think about my almost 85 year old grandma going with us to WDW in February. We won't always be together (she is incredibly independent and loves to go off on her own). I really hope that if she got on a full bus that someone kind would offer her seat. Just out of common courtesy, nothing else. I would do it for your grandma. Just because she can walk all day around the parks, doesn't mean that it still isn't nice to offer your seat. So many people are just plain rude.
No, you don't have to do anything, and obviously most of you on this thread wouldn't offer your seat to someone else and that is just pathetic to me. I see so many people on this board complain about the guests who feel entitled when they are at WDW. Well, maybe some of you should start looking the mirror when you start that complaining. I'm so glad my mom raised me to be a nice person.
BTW--this of course, does not include the people with an unseen issue. Have to throw that in there, of course. Don't want to offend anyone.