www.spacecoastfreewheelers.com
These guys have a few group rides, and some maps of local routes on their site. The River road ride is a good one. The group rides it on Weds night and Sat morning. Route A1A south of Melbourne to Vero is also a good ride. And the Merrit Island Wildlife Refuge/Canaveral National Seashore is great low traffic riding.
www.floridabicycle.org/fbtc
This site has links to organized rides, centuries and such around Florida. Have fun.