I'm down here for work. But like Tech420 said, the only place I feel relatively safe is on A1A and the roads that run parrallel to the beach. A1A has a bike lane which is plenty wide, but in some areas it cuts out after a couple of intersections, and there's some construction by Ft. Lauderdale Beach and on a bridge up north by a lighthouse where I would advise you to take the lane. On A1A people drive 40-50 mph so it can be a little unnerving, but there's plenty of people on bikes around so I would HOPE drivers are looking for them.

That being said, while A1A doesn't have many curves or any elevation, its a beautiful ride, especially in the morning watching the sun rise over the ocean.