While we did not go on any "excursion" in Key West this trip, we did visit the Mel Fisher Museum and highly recommend it. Also, we ate at a place new to us "Hog's Breath Grill" and enjoyed it a lot.. On a prior trip, we visited a local eatery, "B.O.'s Fish Wagon" and again, recommend it if you like conch and other seafood.
Have been here several times. Booked a new tour to the east end of the island and had a GREAT guide and good time... "Island Marketing" (not thru the ship)provided us with two very enjoyable excursions. There is a lot to see and do if you get away from the ship's providers. Only draw back is they have to meet you outside the Port area and it is a long walk up hill most of the way. We did find you can get a taxi inside the port to take you there for $2 per person.
Again we have been here before, but there is so much to do. We again used "Island Marketing" (internet)and had a GREAT day at the beach, just a short ride from the ship, including OPEN bar and food all day... They gave us lounge chairs, umbrellas and non motorized beach equipment.