I had enough stuff I wanted to take I to the concert with me this week that I couldn't fit everything into my pockets but didn't want to bring a purse. I used our daughter's running belt type "fanny pack". It is fairly flat but could wear it covered under my shirt. She will take it when she goes to DC this summer. We are debating on sending her with our good camera, if we do we will get a backpack camera case for her.
yeah I just took my purse in Montreal, but it'll probably be longer days in the cities plus the likelihood of rain is higher. DH is getting a better camera and it will be a bit bigger than the one we had. So we've got this packable backpack thing that he took to FL as a small beach bag that I think we might use.