December Romantic Destinations

Hi all! I'm trying to plan a trip for my husbands milestone birthday this December with a warm getaway. We enjoy biking, road trips, swimming, drinking, and great food. My initial plan was to fly into Miami, rent a fun car and drive to Key West to stay for a few days, but some friends have told me it's not the right "vibe". Any thoughts on Key West or any other city in Florida for a 3-4 day trip in December? Alternatively, any hotel/resort suggestions?