Love all the tips! Just wanted to add a few more. Love Frog Toggs. Purchased mine at Walmart. They stay cool so much longer than any other item.
Be careful which cooling fans or misters you buy. I bought mine from Walmart and after using them only one day they broke. We ended up buying the ones sold in the parks and they were much better quality. Still working one year later and bringing them for our upcoming trip.
I agree ponchos are a must. I would not recommend the ones from the dollar store. As soon as we attempted to put them on, they tore. We purchased the ones in the park and again they were much better quality. Also, if on the plus side they fit better.
For, those who burn easy or are on medication which increases susceptibility to burn, I recommend bringing a hat. I ended up burning my scalp once in a water park and it was very painful, and I have a very thick hair. There also a sunscreen by banana boat for scalps, but not sure how it works.