S.T.
We took our 2 and 4 year old to Disney World last summer and did well with just the regular airplane seatbelt. We brought his blanket with, a few toys, snacks and one of those little DVD players so he could watch a movie. Between the movie, snacks, toys and a short nap with his blanket, we did just fine...I'm sure you will too! Good luck and have fun!! :)