This is what I managed to cram in ours:
full size tub of wipes
toddler flushable wipes soft pack
hard case that is holding about 50-60 trading pins
pin lanyards for the kids
5 drink lanyards
18 pairs of underwear

(preschooler to adult)
15 pairs of socks
cooler
15loads of laundry soap
box of dryer sheets
4 water bottles, 1 with a carrying bag
1 large water container with carrying bag
packets to make up lemonade
full sized shampoo/conditioner/body wash/kid soap
6 toothbrushes
2 tubes of toothpaste
2 boxes of tampons
shower poof
q-tips
face wash
assorted other bathroom needs including contacts
2 full sized sun screens
multiple throw away razors
shaving cream
2 combs
1 hairbrush
15 toy cars
15 littlest pet shops
4 bags of crayons
6 ponchos
stack of blank paper for coloring
kid medicines
adult medicines
band aids
multiple chapsticks
assorted collection of pain relievers
10-12 filters for the brita water bottle
string backpack
cloth laundry bag
a few other things too but I'm blanking on the rest. It's fill to the point that we only have to bring t's and pants and the kids blankets.
I had to bring home the plastic dividers on the plane which earned me a weird look from TSA and thrilled my boys (they make great ramps for cars) and sit on it myself to make it close but it's all in there!
