DH and I, pre-kids, only took one fanny pack and we'd share responsibility for it.
Our first trip with the kids, we took a backpack, that my DH swore didn't fit him.

He refused to play with the straps to make it fit.

My shoulders ached. And all I carried was my small camera, small camcorder, 4 ponchos, 2 autograph books and some snacks. Actually, typing it, it seems like a lot more.
So, this time, we'll be taking 4 fanny packs. The kids will carry their own books and snacks. They'll each have a throw away camera that will be carried, or not, depending on their mood.
I'll have our passes and the camera and DH and I will split the ponchos.
Oogie, may I ask, why do you need your wallet? I put money and my room key in one of the fanny pack pockets. I wouldn't think of carrying the extra weight and bulk of a wallet, even a small one through the parks.