Miami/Key West Road Trip Plan

This is not a definite trip.  In fact, I'm probably about 50/50 on going.  If this one is a go, the date will be MLK weekend because I have a day off work.  I was in Miami for Spring Break back in 2005 and I enjoyed it very much but did not venture beyond South Beach.  I would have liked to have gone at least to Key Largo but my travel companion vetoed that.  A recent google search confirmed that yes, Miami is the furthest south that I have been.  It's close but Miami is about 0.2 degrees further south in latitude than Brownsville, Texas. 

A search on Kayak revealed that a round trip flight from Atlanta to Ft. Lauderdale (30 minutes north of Miami) could be had for just $103.  That's a SMOKIN' DEAL!  Birmingham to Key West is 15 hours driving time so that would be 2 full days of travel each way.  No Thanks.  If it was just to Ft. Lauderdale, I might drive that but not all the way to Key West.  Fun fact:  Birmingham to the Canadian border is CLOSER via car than it is to Miami, Florida by almost an hour.  You can look it up.

Here's what I would probably do:
Friday night: Work a whole day then drive to the Atlanta airport.

Saturday- Early-mid-morning flight to Lauderdale then I'd have to rent a car (ugh) and drive to Key West via the Overseas Hwy.  It's about 4 hours to Key West.  Word on the street is that Key West is somewhat over-rated at least when it comes to beaches but it's a bucket list item and it would be cool to go as far south as you can go.  The drive down, mostly over the crystal clear water ought to be beautiful.  In Key West, you are closer to Havana, Cuba than you are to Miami, Florida and a mere 90 miles from the shores of Cuba.  Crazy.  I'll go out for a couple of drinks at a bar and I am sure to meet some colorful characters.

Sunday- Guess what?  There is a half marathon on this date with a companion 5K.  WHY NOT?  I've already got Florida but North Florida is an entirely different world than South Florida.  After the race, I'll head back up north and stay in South Beach for the night.  I'll have part of the day on the beach on Sunday, all day Monday and part of the day Tuesday.  What's the expected weather in January?  The normal air temperature is about 75 with the water temperature about 72.  A little chilly but warm enough for a swim for sure.  It's also the dry season with only 2.0 inches of rain per month.
I could do this trip with just 1 day off work.

Miami

Key West

EDIT:
There is a direct flight from Birmingham to Miami for $290.  If I fly out of Birmingham instead of Atlanta, I would save money on gas and lodging.  There is sure to be a lot of congestion between Miami and Ft. Lauderdale.  Still, it's probably a net savings of about $75 from Atlanta but it's a LOT more convenient from Birmingham so that's what I'll do.

WEATHER:
Every year, Miami gets maybe 5-6 days in which the high temps don't make it out of the 60s and maybe 1-2 days in the upper 50s.  Low 70s will be okay but below that is too cold for a swim.  If I wait until President's Day in mid-February, my chances of good weather will be a lot better.  It should be at least 75 and may hit 80 by then.  I won't get to race but again, I've already got Florida.  I'll decide shortly before trip.

UPDATE:
I'm leaning towards the President's Day trip with no race.  Hotels are OUTRAGEOUS!  The cheapest ones are upwards of $350 per night and I'd almost have to stay in Key West because it will be so crowded.  As it is, I'll stay in a nearby Key near Marathon for half price and just make a cameo in Key West.