I used to ride my bike a lot when I lived in Miami - to the pharmacy drive-through, around the neighborhood with friends, to the Post Office (back in the olden days, before Click-N-Ship), and to buy barbeque sandwiches and watermelon soda from the guy who worked a bbq stand from his pickup truck. In the summer, it was way too hot to ride during the day, so we'd go in the evenings, when it was a cool 85 degrees or so. If we wanted to ride on a trail, there was a flat, baking-hot loop of concrete that went through Shark Valley in the Everglades National Park - if you wanted the off-road experience, I guess you could try riding over one of the many alligators that sun themselves along the path.
During Michigan summers, it's rarely too hot for me to ride my bike, and there's definitely a shorter season for it, but there are some really pretty trails, with trees, rivers, and hills. We leave the truck at one of the parks, ride the trail around into the downtown area, get ice cream or visit with friends, then ride through town back to the park. I would say it's perfect if the summer in Michigan lasted longer and I weren't wearing an undershirt, long-sleeved shirt, and cardigan as I type this. In July.