poohluvrs - we will be bringing our own strollers to Orlando for all of the reasons you cited. We have BabyTrend Lites and they are FANTASTIC - lightweight, big storage baskets, easy to fold, etc. We use one for each child, and they make it a breeze to get through the airport because our carryons and my purse and DHs backpack fit in the basket.
For some reason DH thinks it would be less of a hassle at MK to rent one double stroller because the kids will probably want to runaround and the double stroller looks like it would be easy for them to get in and out of.
My issue with that is that the twins are dawdlers, and BIG 3 year olds. I don't want to have to carry them from the car to the tram to the monorail to the restaurant, etc.
As you can see, I'm still undecided!