Key West or Sarasota?

This is Sarasota's great advantage. Siesta Key's quartz sand is fine, white and cool underfoot, the water shelves gently with no real waves, and Lido Key, Longboat Key, Anna Maria Island and Venice give you a choice of long, quiet strands.

Key West's sea is warmer for more of the year and very clear over the reef, but its town beaches are small, with imported sand at Smathers and coral rubble at Fort Zachary Taylor. For a beach to compare with Siesta Key you have to drive an hour to Bahia Honda, and most visitors get into the water from a boat instead.

The two eat at a similar level, and Gulf seafood, grouper and stone crab feature in both. Key West has more local character: Cuban sandwiches and café con leche from takeaway windows, conch fritters, Key lime pie and fish shacks around the Historic Seaport and Bahama Village.

Sarasota is more about comfortable bistros and wine bars on Main Street and St Armands Circle, aimed at winter visitors, and its one real surprise is the Amish and Mennonite home cooking in Pinecraft.

Neither place is a big cultural destination, and the two offer very different things. In Key West the town itself is the sight: Old Town's streets of wooden conch cottages and Victorian mansions, plus small house museums for Hemingway and Truman, and a couple of days on foot covers it.

Sarasota has no old quarter, but it has one serious institution in the Ringling, with Baroque paintings including Rubens canvases, the Venetian Gothic Ca' d'Zan on the bay and the circus museum. Fans of mid-century modernism can also seek out houses of the Sarasota School of Architecture.

Key West is the place for a night out. The Mallory Square sunset leads into a long crawl down Duval Street's open-sided bars and rooftop decks, with a long-established gay scene at the upper end, and it keeps going into the small hours. It is loud and boozy rather than stylish, and there are hardly any real clubs.

Sarasota's evenings are quieter and older: a cocktail or glass of wine on Main Street, sundowners in Siesta Key Village, then home well before midnight. Anyone wanting more drives up to Tampa or St Petersburg.

Key West has the better outdoors if you like being on the water. The Florida Reef lies just offshore for snorkelling and diving among rays and turtles, the backcountry flats are known for tarpon and bonefish, and the Dry Tortugas offer remarkably clear water and good birdwatching. On land the island has very little.

Sarasota's strength is wildlife you can reach without a boat: alligators and a treetop canopy walk at Myakka River State Park, dolphins and manatees in Sarasota Bay, and kayaking through the mangrove tunnels off Lido Key.

Sarasota has the more varied list. St Petersburg's Dalí Museum is about an hour away across the Sunshine Skyway, with Ybor City in Tampa, Greek Tarpon Springs and the Edison and Ford estates at Fort Myers also within reach.

Key West sits at the end of the road, so there is far less nearby. Its one outstanding outing, the ferry to Fort Jefferson in the Dry Tortugas, is unforgettable, but beyond that there are only the small towns along the Overseas Highway and the drive across the Seven Mile Bridge.

Sarasota works much better with children. The calm, shallow water off Siesta Key and Lido Key is ideal for small swimmers, Mote Marine's aquarium has sharks, turtles and manatees, and the town is quiet and relaxed. The catch is that you need a car for almost everything.

Key West can be fun for older children who will enjoy glass-bottom boats, the reef and the Hemingway cats, but its beaches are less forgiving and the drinking on Duval Street sets the tone after dark.

Key West is far easier without a car. Old Town is flat and compact, bikes and electric carts are the local way to get about, and nearly everything is within a short ride of Duval Street. A car only helps for trips up the Keys.

In Sarasota you will almost certainly hire one. Downtown, St Armands Circle and Siesta Key Village are each pleasant on foot, but the buses are infrequent and slow, and winter traffic on the bridges to the keys can be heavy.

Sarasota is the slightly better place to browse. St Armands Circle has resort wear, jewellery and galleries in one pleasant ring, Main Street and Palm Avenue have independent boutiques, and a regional mall covers the chains.

Key West's shopping is mostly T-shirts and Key lime souvenirs on Duval, but it does have local character in its Old Town art galleries, hand-rolled cigars and harbour sponge shops.

Neither is cheap, but Key West is the harder on the wallet. Its rooms cost far more than in most American cities because the island has little space to build, and boat trips and the Dry Tortugas ferry add up. You can save by walking or cycling, eating at Cuban takeaway windows and visiting in late summer.

Sarasota gives you more room to manage costs: stay on the mainland rather than the keys, come in summer or early autumn, and the public beaches and state parks cost little or nothing. A hire car eats into those savings.

Sarasota is the place for an evening at the theatre. It has its own opera company in a restored 1920s theatre, a ballet company known for its Frederick Ashton repertoire, a full orchestra season and the Asolo Repertory Theatre on the Ringling grounds, most of it from autumn to spring.

Key West's performances are mainly informal: singer-songwriters in the Duval bars, nightly drag cabaret and the street performers at the Mallory Square sunset. Its playhouses and winter symphony are small in comparison.

Both towns are good for slowing down, and neither has a real bathing tradition. In Key West the calm comes from guesthouses built around small pools and gardens in quiet Old Town lanes, and from the ritual of stopping for sunset, though the bars are never far away.

Sarasota offers spas on the keys, sunrise yoga on the sand and one genuine draw in Warm Mineral Springs, a naturally warm, spring-fed pool about forty minutes south. In both places, winter crowds can take some of the peace out of a stay.