In my fanny pack, I keep my wallet (pared down to the bare minimum) my park pass, gum & camera. There is room for sunglasses when not in use.I use a small fannypack for that.
I carry a small backpack that has a "Park Pack" (small bottle with tylenol,tums,benedryl,gas-ex) purell, shout wipes, bandaids, alcohol swab, sanitary supplies,nail file & clipper, hair bands moisturizer, lip balm & perfume) The park pack is about 4"x6"x2" & weigh's maybe a pound.
Also in the backpack are ponchos, water bottle & sweatshirt or pareo if the weather is iffy or if we are planning alot of indoor, massive air-conditioning events.
My son is almost 16, so I don't have to carry anything for him except for first aid supplies for all of us. Everyone carries their own drink. I will take sweatshirts & ponchos. He often carries a camcorder in bag with pins, gum & camera or his pin bag if we are going to trade....
When DH comes, he carries his own drink & ciggs.