Exile Island? Funky Home to All Kinds of Characters? Cruise Ship Day Stop? All of these and more that is Key West. Spent three days there and here's my opinion, for what it's worth.
People jam Duval Street, heading for Sloppy Joes' or Margaritaville, but places locals head to like Salsa Loca are mich more fun.
Shops have it all, even things you never knew you wanted or needed. Or could afford in come cases.
Street Performers at Mallory Square are free and very good at sunset.
Hemingway House is a nice tour. and lots of six toed cats too.
Some restaurants are very humnble, others very fancy, but food overall is excellent. Try Cafe Marquesa, absolutely outstanding! Or the Grande Cafe.
Parking enforcement is all day long till midnight so avoid driving if you can.
The Trolley sightseeing bus is excellent for getting around in daylight -- two days cost about $58 for two people, less than two parking citations
Be aware that people get pretty happy after midnight, bars close at 4 am.