In Florida, you see most of the sportbikers wearing helmets, but definitely not all. But while they are doing that, you defintely see a lot of folks in shorts and tank-tops and sneakers, too. Near the coast and larger cities, you see a lot of people not wearing the gear, while in the central part of the state, you at least see more people wearing jackets and jeans, if not full leathers.
If I am scooting around town (not often, because I hate riding the bike in traffic), then I will wear a jacket and jeans in addition to gloves and helmet (and always riding boots), but when I go for any real riding, it is the two piece leathers and back protector for moderate riding, or the one piece and back protector for more "spirited" rides.