Given your parameters and that you are already on east coast, I'd be inclined to drive down to FL and so some type of loop that got that missing Sarasota to St Augustine link as well as head out to the keys as well. FL can be some nice cycling in January - I prefer the center more than the coasts due to traffic. However otherwise keep it a somewhat mellow trip and be able to drive both ways.
If I were looking for something more exotic, I'd be tempted to fly to Cuba by way of Mexico City.
The Florida option is definitely still alive, but I am not completely decided. I am not sure I can drive there enough cheaper than flying to make it worth taking the extra time. 2000+ miles of driving puts a pretty good dent in a two week trip and it would be something like $200+ in gas (assuming 30 mpg and not counting any wear and tear on the car). I am actually more concerned about the daily expenses on tour than the airfare in the case of Florida.
Florida does have the advantage of the fact that I left a bike at my daughter's house at the end of my ST tour and that I would be finishing the ST that I already rode most of.
I have always wanted to visit Cuba, but as a US citizen it is kind of off limits. Additionally I work for a defense research lab that requires foreign travel be approved and on a list of acceptable countries. I am not sure if my part time status will end that requirement or not but it is probably better to hold off on Cuba until I have completely severed ties with my employer.