We have a 3 1/2 year old and an 18 month old, and 3 different types of double strollers:
The Double Jogging Stroller;
The Double Cosco Regular Stroller, and
A Double Umbrella Stroller
For theme park type places we usually take the regular Cosco one because it has plenty of storage room, great sun protection tops, and the seats recline for naps and necessary diaper changes.
We reserve the jogging one for outdoor "on the grass" or "bumpy path" type places (boardwalks too!) because it has liitle storage and hard to fold up and carry around. Great for long walks at home, etc.
I love the umbrella for quick trips into mall, etc, but again no storage really and not as comfy for staying in for long periods of time! Very light and easy to carry around, folds up almost as small as the single. I got it at Buy Buy Baby.
It's funny, we had the same three single stollers before number 2 was born, and now # 3 is on the way.......I dread investing in 3 more!! (but I can't seem to just choose one!)
I think we are going to bring are regular double with us in Feb, even though it is big and a little bulky, we loved having it at Sesame Place and Hershey Park this past summer!
Good luck!