If you plan on doing a beach there, I would go to fort Zachary Taylor, it is a state park I think it cost like $5.00 to get in but its the best beach I've been to down there (I go there alot)..gotta watch out for the man-o-wars if you go swimming though. On duval street its all bars and surf shop/tourist shops. Iam going to Key West on an upcoming cruise and I will also just go out and venture on my own. Everything is within walking distance and its a very easy town to get around and small at that. Very tourist friendly!
No matter what you decide to do...you shouldn't be bored