A1A doesn't actually go all the way to Margaritaville: the only highway that serves the Florida Keys is US 1. It does run from Fernardina Beach, Florida to South Beach in Miami, following the Atlantic coast of Florida.

It is not a continuous road, as it detours to avoid inlets in Jacksonville, St. Augustine, Daytona, Titusville, Ft. Pierce, Juno Beach, and Fort Lauderdale. At these points, it merges with US 1 before continuing to the east. The rest of the highway lies on a series of long and narrow islands created by the dredging of the Intracoastal Waterway.

Since it runs next to the ocean, A1A is one of the only truly interesting drives in the otherwise flat and damp state of Florida. It is known as Collins Avenue in Dade County, and Ocean Drive in Broward and Palm Beach: on these stretches, it is lined with alternating clusters of Art Deco motels and billion-dollar condominium towers that define the culture of South Florida. Farther north, you'll find some of the most incredible beaches on the east coast of the United States, as well as the Kennedy Space Center.

Servo5678 informs me that there is a radio station in Cocoa called WA1A, at 107.1 FM.