Sprinke and SCard:
You will get a zillion different answers on this one. It really does depend you your choice, your budget and your children.
I have two kids 2 yrs and 6 yrs. We have been to WDW every year since my oldest was 9 months old. Here's what we do:
We found our double stoller a terrible inconvenience the year we brought it. It was just cumbersome to lug around. Plus the child sitting in back doesn't really get a good view of the surroundings.
Other than that one double stroller year, we do always bring our regular light weight (not umbrella) stroller with us on every trip. Because we want to have it at the airport/the hotel/the stores etc. Think about trying to wrangle a little one when you are NOT in the parks. When the parks close and you have to turn in your rental stroller who is going to carry your sleeping child(ren) to the car? Think about every scenario and if you'll want a stroller, bring one from home. The air carriers let you wheel stollers right up to the gate and you get them back as soon as you are off of the plane. (Do you really want to have to keep track of a little one checking in and when you are claiming your bags at the airport?) Just a couple things to think about when making your stroller decision.
Regarding age appropriateness for strollers. Our little one is in the stoller more often than her big sister. However, the little ones do like to get out and stretch their legs and run around a bit. It is around this same time that my 6 year old usually appreciates taking a walking break and gets in the stroller. Most of the time our 6 year old wants to and can walk around, especially when we are taking breaks by seeing shows, dining, etc. But at the end of the day, both kids are tired and we rotate them in the stroller.
We also like to bring our regular stoller from home because it has a tray and cup holders for the child and the parents, plus the basket underneath is a good place for extra snacks, changes of clothes, the diaper bag and purchases that we don't want to carry around.
That's my 2 cents
