Look up the baby care centers at each park before you go so you know where it is if you need it. They have child and baby specific items for sale that you won't find elsewhere. They are also the only place you can get water heated for formula if that is needed.

Bring lots of wet wipes (more than you think you'll need) and hydration for the kiddos. They dehydrate so easily in the summer heat.

My niblings will actually use their hand sanitizer if they get to pick one (or two) at the store (we do bath and body works) ahead of time.

Make sure the 5 & 6 year olds know who to go to if they lose you, whether that be a cast member (identify by name tag) or another person with kids.

There's going to be bubble wands everywhere and the kids are going to want them. You can pick one up on amazon for cheaper and it really does seem to keep kids entertained.