I'm going after you, but this is a nice ship. I went on it a while back and heard the refurbished it recently. I really don't recommend you take any shore tours in Key West unless you like snorkeling. Key West is relatively small and you can do shopping, dining, sightseeing on your own. The conch train tour will probably take you to the Hemingway house and the Southernmost point, but you can walk it if you're in good shape and have comfy shoes. If you're there for sunset, everyone goes to Mallory Square. They have street performers and vendors as you watch a spectacular sunset.
In Cozumel, the dolphin swims are pricey but worth it if you've never done it before. Hope you have a great time!