Around me, there are multiple iterations of free exercise classes in public places (the ones I like are yoga on the beach and yoga in the park). Weekday evenings are nice, as are weekend mornings. I like to make myself a big bottle of iced tea with lemon in an insulated glass, take a nice leisurely walk to the park or beach, and then do a yoga class. If you want it to be longer than that, you could bring a book for before/after class.
I'm in L.A., so it's admittedly pretty easy here, but I have lots of options for free or very inexpensive open mic nights to watch wannabe comedians work on their set lists. It's not free, because they're usually in bars and it's kind of rude not to buy at least one drink, but you can keep it pretty cheap by nursing a light beer for an hour or two.