Key West is place full of happenings on every corner. The fast paced, restaurant laden little island gives way to some nice beaches around its perimeter. There aren't many hotels or vacation rentals with beach front property. Most of the beaches are public, where you rent chairs and umbrellas. This isn't necessarily a bad thing, but not my preference. I like rolling out of the bed and lazily plopping myself onto a beach at any moment I please.
The atmosphere of Key West reminds me of Cancun, without the infinite run of beach. It's heavily built up and definitely not barefoot and remote. People come here to party, so if that's for you-- then you'd fit right in.
The beaches I went to in Key West.
Higgs Beach: not a favorite. It's small and filled with man of war. Lots of homeless people. Has restrooms.
Smathers Beach: populated but clean. The best sand of all the beaches. This beach has lots of activities like jet ski rentals, parasailing and such. Has restrooms but they are pretty nasty.
Fort Zachery Taylor Beach: this was my favorite beach. Although it had lots of small pebbles getting into the water, the scenery was beautiful. There were trees that lined the entrance of the beach that made it have a campground feel. The restrooms were very clean. It costs to even get into the area though. I think it's worth the money.
Other things to do in key west
Take a conch train tour
See the Little Truman House
Hemingway house
There are lots of sunset cruises
Eat Key Lime Pie
Visit the Turtle museum
See art galleries on White street
Eat a Cuban sandwich
Other Restaurants I liked that I didn't review
Panini Panini on Duval. Good inexpensive lunch. Not cheap for a sandwich but cheaper than most places.
Key West Cakes. Get a lemon cupcake.
Tips:
Rent a small doorless car or bike so you can get around.
If you want to eat at any of the nice waterfront restaurants, make a reservation before you go.
There are Laundromats all over the island if you want to was clothes-- most close at 9pm.