Practically every parish throws a summer festival for fundraising, and there are usually multiple festivals every weekend. There’s free music of the cover-band variety, and lots of great people-watching. (And beer, but of course that’s not free.)
17. Picnic in the park
The best place to park it when you’ve got a picnic in hand is at one of the many beer gardens. Estabrook Park, Hoyt Park, and Humboldt Park are the best, and generally have live music. You can bring picnic baskets (and dogs!) into any of them.