Way too many clothes. We have gradually learned take enough socks and undies for each day, and just a couple of changes of outer clothes, make use of the laundry facilities.
But the snack thing we really need to bring the snacks. I have older kids (17,15,11) and they were responsible to carry (in a fanny pack or over the shoulder small camera-type bag) a water bottle, their own spending $$, a snack or 2, and a camera if desired). They knew we planned on a late lunch/early dinner thing every day, and sometimes they got hungry before 2 or 3 o'clock. I know this probably wouldn't work for younger kids, but for the older ones, they wanted to go off on their own some of the time, and didn't need to worry about snacks coming from their $$.