We did a "Haunted Key West" tour. It was a fun way to see the area. It started at 9 am, not too scary at that time.
We also did the Mel Fisher Maritime Museum, where the artifacts from the Atocha which sank in the 1600s are displayed. They have beautiful items on display, gold bars, jewelry, weapons. They have a website, if you want to check it out. I would definately recommend it, if your into history. I think Hemingway's house is there too. Hope this helps, Lil' Lori