Not a bad idea at all Tandem Tom. I don't want to discourage anyone from riding this route, or any route for that matter, if that is what they want to do. This route, however, was very challenging for us, and when I say that, I am comparing it to riding through the likes of San Francisco, L.A., San Diego, Phoenix, Austin, Washington D.C. and the list goes on. The route through the Miami area was absolutely terrifying compared to any of these other cities. To be fair, we were riding at what was probably the worst time, Spring Break season, and rush hour through this section. There was just too much road through the Miami are with no shoulders, no bike lanes, and the side walks (which I hate riding on) were even posted that cyclist were not allowed on them.
It was extremely stressful, car honking and people yelling out their windows at us, a few people even threw trash at us.

Then, riding through Miami from West to East on the Tamiami trail was a whole other adventure. We were advised by a local professor at one of the colleges on which neighborhoods were dangerous, which led to us mapping and riding an extremely circuitous route through the city that took forever. Other than Miami being a hellacious experience both times we went through, and the ferry not letting us on after we booked it in Key West, the ride was a lot of fun. We were just left with a sour taste in our mouths. Florida doesn't exactly go out of their way to make bicycle friendly provisions.

With that, all I can say is that the Keys are much more relaxed, and a neat place to visit. Overall I wouldn't do this trip by bike again. Two days of feeling like I might die at any moment in Miami was plenty for me. Hopefully everyone else will have a better experience than me.