Our first trip our boys were 3.5 and 5.5 and we didn't use a stroller. We were past using one by over a year at that point for youngest DS. They never complained about being tired and youngest DS rode on his dad's shoulders for a few minutes a couple of times in Epcot. It was 1989, so only three parks, but because we didn't use one at home, they never complained. They were 28 months apart and I never had a double stroller either.