Billy,
Your right in a way, theres plenty of beaches in Key West, not beaches as you would call them compared to the East & West coasts of Florida.
All the beaches in Key West are man-made with most of the sand transported from the Bahama's, are coral islands, former reefs, from when the ocean was deeper. Today, the ocean is shallower and the reefs are six miles offshore, providing a barrier to wave action, thus, with little sand to begin with, and a lack of wave action to deposit more, beaches in the Keys are a bit of a rarity.
Pier House, Hyatt Resort, Casa Marina Resort (largest private beach), The Reach Resort & a few others have very small beaches used for clothing optional or just wadding in the water with whoever.
Here are some of the beaches in Key West & most are very nice for sunbathing or whatever:
Fort Zachary Taylor State Park Beach - everyone kinda goes there cause of the Wonderful sunset views. One of the best beaches in Key West, though a bit rocky. Public restrooms, food/drink kiosk, chair rentals, picnic tables and BBQ's. Admission charged. Entrance through Truman Annex at Southard Street.
South Beach - A favorite of locals, nice sandy beach with shallow waters and a concrete pier. No restrooms or facilities, located at the end of Duval Street on the Atlantic Ocean.
Higgs Beach - Wide sandy beach with long wooden pier, restroom facilities, covered picnic tables, full service restaurant, playground, chair rentals, rafts and watersports rentals. Located at the end of Reynold's Street.
C B Harvey Rest Beach or White Street Pier - Soft sand and natural vegetation, home of the White Street Pier where you can enjoy some great fishing. Wheelchair accessible, Yoga deck with nightly classes, restrooms within walking distance, picnic tables. Located at White Street on Atlantic Ocean.
Smathers Beach - Half mile stretch of sandy man-made beach, restrooms, ample parking, concession stands, chair rentals, bike paths, picnic tables, volleyball nets, watersports rentals - jet skiiing, parasailing, and windsurfing. Locared at South Roosevelt Boulevard & this is where most of the young ones go, also, Spring Breakers.