With our shift to Florida's drier, milder season, local cyclists and visitors alike may reasonably think of venturing down the Florida Keys on the Overseas Heritage Trail. At that state website you can find links to a 48 x 36-inch map and a pair of cue sheets to help you ride smarter.
Riders coming from or through Miami can follow the South Dade Trail alongside the busway to Florida City, then use the new, wider shoulders on U.S. 1 down to Key Largo. Often group riders will choose Card Sound Road for that stretch, on the theory that cars drive slower on the narrower road. However, I'd recommend staying to the larger road because the shoulders give you more room to ride.
Either way, you should be as well-prepared as possible to deal with the consequences of glass and other road debris. Avoid night riding, and if you must ride at night the light your bike front and back.