What bag to carry???

[Windy City Heather]

I have never thought to much of this because we have taken our own stroller. Just so long as the bag fit under the stroller I was happy. My husband does not want to take our own stroller and just rent as needed. DD does not like being in the stroller anyway. I have to carry at least one change of clothes if not two because I can't trust her to stay dry. I will need my camera (which is small), sun block, tickets and a couple of small things. I will carry one thing of small snacks and I like to have a bottle of water. Also, autograph book and pen.

What bag should I look into?