Key West or Miami Beach?

Miami Beach wins this easily. The whole Atlantic side of the island is wide, pale sand, and you can pick the mood, from the people-watching and pastel lifeguard huts of South Beach to the space of North Beach. The price is sharing it with crowds, music and vendors in the busy stretches, and water that is green-blue rather than clear.

Key West's water is just as warm and calmer, sheltered by the reef, but the shore lets it down. Smathers has imported sand, Higgs is a small local spot, and Fort Zachary Taylor's clear water comes with coral rubble underfoot. For a proper beach day, most people drive the hour to Bahia Honda.

Both places share the Cuban takeaway window, the winter stone crab and a tourist strip best avoided, Duval Street in one and Ocean Drive in the other. Beyond that, Miami Beach goes much further. Chef-driven dining rooms, ceviche and arepas from South American communities, Latin cafés in North Beach and Little Havana across the causeway give a week of different meals.

Key West is narrower but has its own charm: pink shrimp and grouper at dockside shacks around the Historic Seaport and Bahama Village, conch fritters, and arguments over which Key lime pie is best. It is enough for a few days rather than a food trip.

In both towns the buildings are the main attraction, but they tell different stories. Key West has white wooden conch cottages and verandaed Victorian houses under banyans, while Miami Beach has 1930s pastel stucco hotels with neon and porthole windows along Ocean Drive and Collins Avenue.

Miami Beach adds more beyond the streets: the Wolfsonian's design collection, contemporary art at the Bass, the Holocaust Memorial, and the larger mainland museums close by. Key West's sights are smaller and more personal, with Hemingway's six-toed cats, Truman's Little White House and the treasure from the old wrecking days, and two days covers them.

Miami Beach is the bigger night out. South Beach clubs with guest DJs run until dawn, hotel pool parties start in the afternoon, and dress codes, door policies and table service set a glossy, expensive tone. Sunset Harbour offers quieter cocktail bars for those who want them.

Key West is just as late but far more casual. Evenings begin with sunset on Mallory Square and drift along Duval Street's open-sided bars and old saloons, drink in hand and in shorts, with a long-established gay scene at the upper end. There are hardly any real clubs, so anyone after dance music should choose Miami Beach.

Key West has the better outdoors, and almost all of it is on the water. The Florida Reef is a short boat ride away for snorkelling with rays and turtles, the mangrove backcountry suits paddleboards and sight-fishing for tarpon and bonefish, and the Dry Tortugas add remote islands and seabirds.

Miami Beach relies more on day trips: the Everglades, with airboats and alligators, are about an hour's drive away, alongside Biscayne National Park's reefs and the mangrove trails of Oleta River. Neither place has hills or real hiking.

Miami Beach has far more within reach. Across the bay are Little Havana, the Wynwood murals, the Vizcaya villa and gardens and the Mediterranean Revival streets of Coral Gables, and Fort Lauderdale and Palm Beach are within about an hour and a half to the north.

Key West sits at the end of the road and has one standout outing: the ferry to Fort Jefferson, a huge brick fort on a tiny island. Otherwise there is the drive over the Seven Mile Bridge to Marathon's turtle hospital and Islamorada's marinas. Miami itself is too far for a comfortable day.

Key West has more small attractions for children than its reputation suggests: a little aquarium, the shipwreck museum, the butterfly conservatory, and trolley tours that save young legs in the heat. Old Town's quiet residential lanes are easy to cycle as a family. Fantasy Fest in late October is firmly adult, so plan around it.

Miami Beach still works better for a family stay, thanks to the resort pools and the condo-lined stretches towards Surfside, where the days can be built around the water. On the island itself little is made for children, and South Beach fills with spring break crowds and weekend noise. In both places, summer heat and storms mean keeping the outdoor hours to the morning and late afternoon.

Both are flat and easy without a car, but in different ways. Key West is a bicycle town where everything sits within a short walk or ride of Duval Street, and public transport barely exists. Miami Beach adds free trolleys and county buses up Collins Avenue, along with bike share on the beachwalk.

Leaving is where both get harder. Key West has only the single Overseas Highway up the Keys. From Miami Beach there is no rail link, so trips to the mainland mean buses or cars stuck in causeway traffic.

Miami Beach has two real places to shop. Lincoln Road is Morris Lapidus's palm-shaded pedestrian mall of international chains, and Bal Harbour at the island's northern tip gathers the big European fashion and jewellery houses. Local crafts and markets are scarce, though.

Key West is mostly T-shirts and Key lime soap, but what it does have is more local: tropical art galleries in Old Town, hand-rolled cigars from the island's cigar-making past, and sponge and shell shops by the harbour.

Neither is cheap, and they are expensive in much the same way. Key West's limited land keeps room rates high, and the boat trips and the Dry Tortugas ferry quickly add up. Miami Beach piles resort fees, parking charges and service charges on top of the room rate, and South Beach cocktails and club entry are steep.

The ways to save are different, though. In Key West you can walk or cycle everywhere, and the Mallory Square sunset costs nothing. In Miami Beach the side-street and North Beach hotels, the free trolleys and the free beach help. Summer is the cheaper season in both.

Miami Beach has a proper arts season from autumn to spring. The New World Symphony plays in its Frank Gehry hall, with some concerts projected onto the outside wall for crowds on the lawn, and Miami City Ballet and the Jackie Gleason Theater add dance and large touring shows.

Key West is more about informal performance: singer-songwriters and cover bands in every Duval bar, nightly drag cabaret, and jugglers and trained-cat acts at sunset. Bands are easier to find here, since Miami Beach's clubs lean to DJs.

Miami Beach does pampering better. Large resort spas with saunas, steam rooms and plunge pools, sunrise yoga on the sand, and the calm pool-side stretch of Mid-Beach towards Surfside make for a restful week, if you pay for it.

Key West's calm is smaller and more homely: guesthouses built around little pools and gardens, quiet Old Town lanes, and the daily pause for sunset. Neither has a bathing tradition, and in both the party streets are close by, so where you stay matters.