I guess I'm kinda the lucky one, since my mom STILL pays for vacations! I think she does this because A. we can't really pay since she uses the military stuff (but we could still give her cash), B. She wouldn't take any money from us anyway - she's one of those parents who simply loves Disney and loves being around us and C. she now has a grandchild who she loves seeing and loves being around, and I guess I come with the package.
Our family has always been one of those "fight over the check" families anyway. When the bill for meals would come, my grandfather always insisted in paying for it - my mom and dad always had to ask the waiters to slip them the check. My grandma and grandpa got SOO mad when someone else paid for them. In terms of paying/not paying, think long term. They are your babies, no matter what, and how long do you get to be with them and take care of them? Yes, we want kids to be independent and "launch" into the world on their own, but there are some times when you simply want to treat them.
And yeah, I'm lucky and pretty spoiled, I know.