Be sure and visit Fort Zachery Taylor Park -- this is a great place to watch the sunset. Nancy's Secret Garden is a special spot in the heart of old town -- be sure to visit.
Quick Tips: Since Key West is such a popular destination, I would advise making reservation early, especially if you have a particular place you want to stay. In our case, it is the Frances Street Bottle Inn. This also holds true for restaurants, the popular ones book fast so be sure and have the staff make a reservation for you early in the day.
Best Way To Get Around: Walk, walk, walk (you can always call a taxi if you get tired), or rent a bike.