Key West or Myrtle Beach?

For a day on the sand, Myrtle Beach wins easily. It has some 100km of wide, pale beach shelving gently into small waves, with calmer stretches backed by dunes at Surfside and Garden City. Key West's town beaches are small, either imported sand at Smathers or coral rubble at Fort Zachary Taylor, and the nearest classic beach is Bahia Honda, an hour up the highway.

What Key West has instead is the water. It is clear, calm, sheltered by the reef and warm right through the winter, when the Atlantic off Myrtle Beach is too cold for most people. The greenish Carolina sea is for a summer swim. Key West's water is for a snorkel mask.

Both are seafood towns with a narrow range, but Key West has more of its own flavour. Cuban coffee and sandwiches come from takeaway windows, stone crab arrives in the cooler months, and locals argue over Key lime pie slice by slice.

The Myrtle Beach strip is mostly buffets, pancake houses and chains. Its best meals mean driving to the docks at Murrells Inlet or across the state line for Calabash-style fried fish, with shrimp and grits as the Lowcountry dish to look out for.

In Key West the town is itself the sight. Old Town is a large district of conch cottages and Victorian verandas, and the Hemingway house, Truman's Little White House and the shipwreck treasure collections fill two days well.

Myrtle Beach is a twentieth-century resort with little of its past on show. Its one real draw is Brookgreen Gardens, which sets sculpture among live oaks on a former rice plantation, with Atalaya next door, and a single day covers both. For more history, make the drive to Charleston.

Both go out loud and casual, but Key West does it with more conviction. The evening starts at sunset on Mallory Square, then moves to Duval Street, a walkable run of open-sided bars and old saloons that stays open into the small hours, with a long-established gay scene at its upper end.

Myrtle Beach has more actual dancing, in the clubs of the big entertainment complexes and the shag clubs of North Myrtle Beach. Its nights are more seasonal, though, often need a drive between places and mostly wind down early outside summer.

Key West's outdoors happens on and under the water: the coral of the Florida Reef a short boat ride out, mangrove flats for kayaking and bonefishing, and the remote Dry Tortugas. Myrtle Beach offers gentler scenery of salt marsh, maritime forest and cypress swamp, with alligators and herons at Huntington Beach State Park and paddling on the Waccamaw River.

Neither has hills or hiking. Golf is the one area where the Grand Strand comes out clearly ahead, with dozens of courses along the coast.

Myrtle Beach has more to choose from. Charleston's antebellum streets are about two hours south, and Georgetown, Wilmington and Southport are closer, though every one of them needs a car. From Key West the only road leads back up the Keys to small towns such as Marathon, and Miami is too far for a day.

Key West's one great excursion is the ferry to Fort Jefferson in the Dry Tortugas, a remote island fort with nothing like it on the Carolina coast.

Myrtle Beach is built for children: gentle surf, resort pools with lazy rivers, kitchen suites, an aquarium, water parks, a wooden roller coaster and endless themed mini-golf. Key West can work for families who love the water, with glass-bottom boats, reef snorkelling and the calm shallows at Fort Zachary Taylor.

Beyond that, Key West's centre revolves around the drinking on Duval Street, and there is far less to fill a week with younger children. Summer heat needs planning in both places, and families should avoid Myrtle Beach during spring break.

Key West is small and flat enough to walk or cycle everywhere, and a car is a nuisance in Old Town. Myrtle Beach is the opposite. Its attractions are spread along multi-lane highways with few pavements, and summer traffic on Kings Highway moves slowly.

The gap narrows at the edges. Leaving Key West for the rest of the Keys means driving too, and within Myrtle Beach's oceanfront blocks the beach itself makes a long, flat walkway.

Neither is a reason to travel for shopping, but Myrtle Beach gives you more places to spend: two big outlet centres, lakeside complexes and the Market Common on the old air base. Key West has no fashion to speak of, though its Old Town galleries, hand-rolled cigars and harbour sponge shops make for more distinctive browsing than the Grand Strand's huge beachwear stores.

Myrtle Beach is far cheaper, thanks to its huge supply of motels and condos, many with kitchens, though a rental car is almost unavoidable. On Key West, limited land and strong demand make rooms cost far more than in most American cities, and boat trips and the Tortugas ferry add up quickly.

Timing matters in both. Myrtle Beach is cheapest outside July and long weekends, and Key West in the hot, stormy late summer. Key West's one saving is transport, since a bicycle gets you everywhere.

Key West offers the broader range. Its formal scene is small and thin in summer, but the Tennessee Williams Theatre and a couple of intimate playhouses stage plays, and a symphony orchestra performs through the winter season. Around them runs a constant informal layer: singer-songwriters in the Duval bars, long-running drag cabaret and the jugglers and tightrope walkers who perform on Mallory Square at sunset.

At Myrtle Beach, orchestral music and serious drama barely register for a visitor. The city's strength is big, polished variety instead: country and gospel revues, dinner shows with knights or pirates, Christmas shows and touring country and rock acts at the main entertainment complex. That makes an easy evening out with children, but there is not much for anyone hoping to see a play or a concert season.

Key West is the better place to slow down, with guesthouses set around small pools and gardens in quiet Old Town lanes and a town that stops for sunset. In summer the main strip at Myrtle Beach is loud and car-bound, so rest there means a resort spa, or the quieter southern end around Pawleys Island in spring or autumn. Neither has any bathing tradition.