Driving or flying into Key West? Tons of things to do if driving through the Keys. Key Largo, Islamorada, Marathon, Big Pine, Key West. KW gets all the attention but some of the best spots are in the other parts. If you're there during a full-moon, check out the full moon party in Islamorada. If you like marine mammals, several dolphin/sea lion shows in the Keys (Theatre of the Sea- Islamorada, Dolphin Connection- Duck Key, Dolphin Research Center- by Marathon). In Key West, do the Crawl, Irish Kevin's, Mallory Square Sunset Celebrations, Hemingways 6-toed cats. The best places are the small hole-in-the wall bars/restaurants, not the chains (Hard Rock, Margaritaville, etc.).
Used to live there, have fun, it's a great place to visit.