Hikpro waterproof backpack (it folds very compact for the suitcase if you don't wanna take it on the plane). 2 frozen Water bottles in insulated carriers to catch condensation (fit in the sides), sunscreen, 02 cool caribiner cooling fan, frogg togg towels in ziploc bag (2 cut in half for the 4 of us), cell phones in outer pocket, hand sanitizer, Motrin, ponchos, kleenexes, feminine products in a ziploc bag (just in case!), snacks, sandwiches (it gets lighter throughout the day and I make DH carry it, lol)
We also take a cinch sac for our pin lanyards (too heavy to wear), autograph books, penny presser supplies (little container with quarters and pennies ready to go), and flip flops for my girls if their sneakers get wet - they don't like Teva's