Actually, Hemingway never hung out at the bar currently called Sloppy Joes. The old Sloppy Joes is now Captain Tony's Saloon. Hemingway had left Key West before the current Sloppy Joes was established using the old bar's name, though they certainly won't tell you that at Sloppy Joes. They capitalize on the incorrect notion that Hemingway hung out there, but a few minutes of research on the Internet will reveal the truth.
Robbie's is the name of the place south of Islamorada where you can feed the tarpon and I HIGHLY recommend it. Order your breakfast and go feed them while you're waiting. Lay down on the dock and hang your arm over with the fish if you dare. We all had a great time there. Definitely one of the most memorable parts of our trip.
Don't go to The Keys looking for beaches. There is only one natural beach (Bahia Hondo) and it's only okay.
Have fun!