Our trip last year we didn't take a stroller, as we new we could rent them. I don't like paying $12-$13 a day for a double stroller or two singles. This year we brought our own, BIG, SUV as I like to call it. Monorail was the only way to travel for us. The busses were bad, but only when it was really crowded, after Fantasmc!
I can't imagine having to carry either of my sons, 2 and 4, at the end of the day. I was beat. That's what I get for taking a red eye flight, but that's another story.