You're heading to Key West, that's awesome, the food scene there is incredible. I've been a few times and I always make it a point to try some of the local favorites. For seafood, you have to check out Louie's Backyard, their grilled mahi mahi is to die for. Another spot I love is Blue Heaven, it's a quirky little place with amazing breakfast dishes like lobster benedict. If you're looking for something a bit more low key, El Siboney Restaurant is a great spot for some authentic Cuban cuisine, their ropa vieja is so tender and flavorful.