Key West or Palm Beach?

Key West's sea is warm and kept calm by the reef, but the island's own beaches are modest. Smathers is a strip of imported sand, Fort Zachary Taylor has coral rubble underfoot, and seagrass fills the shallows. The nearest classic beach is Bahia Honda, an hour's drive away, so most visitors spend their water time on boats.

Palm Beach is the beach destination of the two. The whole ocean side of the island faces the Atlantic, with public stretches at the Municipal Beach and Phipps Ocean Park, and wider sand at Singer Island, Juno and Delray within half an hour. You can lie on sand and swim every day without planning around it.

The two are broadly level and share a seafood menu of grouper, snapper, stone crab and Key lime pie, but they differ in tone. Key West eats casually: Cuban sandwiches from takeaway windows, fish shacks by the Historic Seaport, chickens under the outdoor tables.

On the island, Palm Beach means formal French and Italian rooms where dress codes matter. Across the bridge, West Palm Beach adds Cuban bakeries, Caribbean takeaways and a waterfront green market, so the range is a little wider, if rarely memorable.

Neither takes more than two or three days, and their heritage comes from different worlds. In Key West the sight is the town itself: streets of wooden conch cottages and cigar-era houses, plus Hemingway's house and Truman's Little White House, telling a story of wreckers and writers.

Palm Beach's story is Gilded Age money, seen in Flagler's marble Whitehall and Mizner's courtyards along Worth Avenue. It also has a real art museum in the Norton, which Key West cannot match.

Key West is clearly the place to go out. The evening begins with sunset on Mallory Square and carries on along Duval Street, where people drift between open-sided bars and rooftop decks until the small hours. A well-established gay scene sits at the upper end of the street.

Palm Beach island is in bed early, and much of its social life happens in private clubs. Clematis Street in West Palm Beach has bars and a couple of dance spots, which are fine for a night or two.

Both are at their best underwater, and they get there differently. Key West's outdoors means going out by boat: snorkelling trips to the Florida Reef, fishing the mangrove flats for tarpon and bonefish, and the remote Dry Tortugas. There is almost nothing to do on land.

Palm Beach offers shore diving under the Blue Heron Bridge, known for octopus and seahorses. It also has more on dry land: the Lake Trail by bike, alligators along the Loxahatchee boardwalks and river paddling in Jonathan Dickinson State Park.

Palm Beach has far more within reach. Miami's South Beach, Little Havana and Wynwood are about an hour away by fast train, and Delray, Boca Raton and the Jupiter lighthouse make easy half-days.

Key West sits at the end of the road. It has one outstanding outing, Fort Jefferson in the Dry Tortugas, and otherwise there is the drive over the Seven Mile Bridge to small towns such as Marathon. Miami is too far for a comfortable day.

Palm Beach is the easier family base, though most of the fun is across the bridge. Children have the zoo with its jaguars and panthers, the science centre and aquarium, manatees at Manatee Lagoon and a drive-through safari park, and Peanut Island's lagoon is good for small swimmers.

Key West works for children mainly on the water, with glass-bottom boats and calm shallows at Fort Zachary Taylor. Its few indoor attractions are small, and Duval Street's drinking and Fantasy Fest are firmly adult.

Key West is much simpler to get around. Old Town is flat and compact, bikes are the local way to travel, and a car is more trouble than help in the narrow streets.

Palm Beach is walkable only around Worth Avenue and downtown West Palm Beach. The zoo, reserves and northern beaches are spread out, so most visitors rent a car. The fast train to Miami is its one real advantage.

Palm Beach is a genuine shopping destination. Worth Avenue has luxury houses and jewellers set among Mizner's vias, the consignment shops sell designer pieces from wealthy local wardrobes, and Antique Row lines South Dixie Highway with dealers.

In Key West, shopping is something to do on an evening walk: T-shirts and Key lime soap on Duval, with Old Town galleries and hand-rolled cigars as the more interesting finds.

Both are among the most expensive places to stay in the country, and neither is cheap at any level. In Key West, the savings come from its small size: you need no car, the Mallory Square sunset is free, and Cuban takeaway windows are fair. The costs build up through boat trips and diving.

In Palm Beach, the usual trick is to sleep in West Palm Beach or further along the coast and drive over. In both towns, the hot summer is the time when rates fall.

Palm Beach has the more serious stage. The Kravis Center hosts touring Broadway shows, ballet and Palm Beach Opera, and Dramaworks puts on serious plays. The catch is that almost all of it happens in winter.

Key West's performing life is informal and nightly. There are singer-songwriters in the open-air bars, a long tradition of drag cabaret, and jugglers and tightrope walkers at sunset on Mallory Square, with only small playhouses for anything more formal.

Palm Beach is the more restful stay. The island is manicured and hushed, and its large oceanfront resort spas, with salt-water pools and treatment menus, are built for days of doing very little.

Key West can be just as slow in Old Town's guesthouses around small pools and gardens, but the party on Duval is never far away, especially at weekends and during festivals.