Originally posted by IowaGirl
Gosh, one other thing
When we were this May, I was astonished how much stuff was left behind by people in their strollers when they went for a ride. I felt comfortable leaving behind my little cooler of ice bottles (which we did) and I would have left a diaper bag (if I had still needed one), but I saw cameras, souvenier bags, really nice Disney Diaper bags, etc. I am sure theft happens there too
It sure does, it happened to a family in my dd's class. They had their camera, cellphone and important prescriptions in a camera case. They left it on a bench with Grandma ... Grandma wandered off thinking "it'll be safe, this is Disney."
They lost a half-day of vacation making calls to cancel the cell phone account and re-fill the prescription. A lesson hard-learned.
Ok, to answer the original question - I am used to carrying weight on my hips

so I got a very small squarish pack with a shoulder strap that ends up at hip height. In there goes money, ccs, room key, camera, comb, pen, sunglasses - that's about it.
If the kids are along for the trip, we use a backpack exactly like beattyfamily described. We have an average-sized Jansport. We leave it in the stroller when we go on rides, unless we do have the cameras in there, then we bring it of course.
For the rare trip without the kids, I have a small flowered backpack I got at Target. My own snacks, water bottle, hat, extra film, even a light jacket all fit in it great. It is cloth, because in hot weather I hate the sweaty feel of nylon backpacks. It is pretty enough to work as a "purse" for dressier occasions.