Key West is a great place to do your own thing. Any particular interests, or just the touristy stuff? Go to Mallory Square and there is a lot of stuff to see and do. Buy an all-day pass on the Old Town Trolley and you can go everywhere it goes, and get on or off when and where you want. Another trolley will be along every so often. Don't confuse this with the Conch Train, which doesn't have the come and go option.