I think I have just about brought everything you can think of, the biggest hits with my family go like this. While this isn't everything just the highlights.
Homemade muffins and lemon pound cake - I have to make these " Trashcan Cookies" is what my family calls them I use a oatmeal cookie recipe as the base and just throw whatever I have in them, they are super filling and not to unhealthy..

Pop Tarts, breakfast bars, mini bagels with cream cheese
Grapes, and or Cuties ( little oranges)
1 large box of cereal
Milk and juice/ juice boxes this is a huge money saver with little kids ask for a glass of ice and squeezing the juice in and cold juice ready to go.
Case of water
Soda, Gatorade
Small Individual bags of crackers, peanuts, trail mix, chips, pretzels,
Cheese stick or baby bells, baby carrots, and those packages of celery pre-cut and a small bottle of ranch for dipping or use the cream cheese too.
Deli meat and sliced cheese to roll-up and snack on ( in room and pool side)
Adult beverages - I bought a plastic container with one of those freezer sticks it will hold a whole bottle of wine, pool side drinks.
Don't forget paper plates, and bowls, some kind of plastic forks and spoons, napkins, paper towels, baggies quart and gallon
Since your driving invest in a rolling cooler

for the room it so much easier than those tiny frig's that I don't really trust or never really get cold. Also a small cooler to take to the pool, we use a soft sided collapsible cooler works great. We have used it for the ride home for wet swim suits one time...