The Pinellas Trail runs thru the entire St. Pete area all the way to Tarpon Springs with bridges over the main highways.
http://www.pinellascounty.org/trailgd/ The trail is probably not the best for fast cycling as a lot of pedestrians use it also, but you are seperated from the cars. We rode the entire length up and back one weekend and had a good time. As for the rest of the area, it is similar to the rest of Fla, some bike lanes, lots of old people in giant cars and the regular crazies.