What time are the fireworks that night? My kids are pretty high energy so they would have no issues with that schedule. Even though your day is busy, you're not really doing a lot of tiring things. Sitting at BBB for a makeover and having 2 meals in the castles are not tiring! It's the running around doing rides and standing in lines that most people find tiring (and we do a LOT of running around!) If you really need a break in the park, just find a spot to sit and have a snack or watch a show.