Yea, I think it is just a familiarity thing. And maybe the animals.
I find one thing pretty consistent when it comes to my children and vacation. They get excited about what I get excited about.(and DH ofcourse)
They have stayed at a Value- AMo, a moderate - POR, and a deluxe - WL. They were crazy excited about ALL of them. And you know why........BECAUSE THEY WERE AT DISNEY!
This time we are off site. They are off the wall excited because they will have their own bedroom, seven pools and I told them they could spend some time in Mommy and Daddy's jaccuzi. (it's in the Master bedroom, and from the pictures, it's so big, I think all three of them can fit in at the same time)
Most of our friends have not been to WDW and the ones that have only go every four or five years, if that. They think WE'RE the crazy ones, and we only go every other year or so.

So my kids know that they are very fortunate to have gone as much as they have.
Maybe their attitudes will change as they get older. I'm sure they will have their likes/dislikes. I mean, we do, right??
