You can get a sense of how much of the Overseas Greenway has been completed from this map: http://www.dep.state.fl.us/gwt/state...s/fkohtmap.pdf
For the 100 miles I rode, I pretty much stayed on the highway since the Greenway trail was maddeningly inconsistent

drjava is right on- 99% of the bikes you'll see on the island are SS cruisers. Eaton bikes was the only "real" bike shop I could find in town. They were stoked when I told them how many miles I'd put on their Kona Jake rental.