Palm Beach or St. Petersburg, Florida?

Both are first-rate beach places, but the water behaves differently. Palm Beach faces the Atlantic, and the Gulf Stream keeps the sea clear and warm enough for a proper swim even in January. The island's own sand is narrow in places, though, and much of it sits behind seawalls and estates.

St. Petersburg's Gulf beaches at St. Pete Beach and Pass-a-Grille are wider, whiter and calmer, and Fort De Soto has a wilder stretch. The winter sea turns cool, and the sand is a short trip west from downtown rather than on the doorstep.

Neither is a food destination, and the difference is mostly in tone. Palm Beach eats formally, in Italian and French dining rooms and over terrace lunches off Worth Avenue where dress codes matter, with West Palm Beach's Cuban bakeries and green market for something looser. St. Petersburg is barefoot by comparison: grouper sandwiches and smoked fish spread in Pass-a-Grille fish shacks, brunch along Central Avenue, and craft beer taprooms all over the city.

St. Petersburg has the stronger museums. The Dalí Museum is worth the trip on its own, and the Museum of Fine Arts, the Chihuly glass and the Arts and Crafts museum are all within walking distance on the downtown waterfront. Murals also cover the walls of the Central Arts District.

Palm Beach offers less, and what it has is mostly about wealth and architecture: Flagler's Whitehall mansion, Mizner's Mediterranean Revival vias and the estates along South Ocean Boulevard. The Norton Museum of Art is across the lagoon. Either city fills two or three days, but St. Petersburg gives those days more variety.

Neither stays up late, but St. Petersburg gives you more to do after dinner. Central Avenue's cocktail bars, rooftops and brewery taprooms are close enough to walk between, and on the beaches the evening starts with sunset at the tiki bars. For a rowdier night, Ybor City is across the bay.

On Palm Beach the island is asleep by eleven, and much of its social life happens in private clubs. Going out means crossing to Clematis Street in West Palm Beach, which is fun once or twice but soon feels small.

The two are level outdoors, and both are flat, subtropical and shaped by water. The difference is whether you go under the water or stay on top of it. Palm Beach is the place to go under: reefs lie close offshore on the Gulf Stream, and the shallow dive under the Blue Heron Bridge is known for seahorses and octopus. The Loxahatchee refuge inland has alligators.

St. Petersburg is better on the surface. Paddling trails at Weedon Island and Shell Key run through the mangroves among dolphins and rays, Fort De Soto is good for birding, and the long Pinellas Trail makes for easy cycling.

From Palm Beach, nearly every good day out leads to Miami, an hour south by fast train, for Art Deco South Beach, Little Havana and Wynwood's murals, with Fort Lauderdale's canals on the way. Closer to home, Delray Beach, Boca Raton and Jupiter's red-brick lighthouse are pleasant, but they feel much alike and offer little older heritage.

St. Petersburg has no single draw on Miami's scale, but its outings are more varied: Ybor City's cigar-factory streets in Tampa, the Ringling's Venetian-Gothic mansion in Sarasota and the Greek sponge docks of Tarpon Springs. Orlando's theme parks are at the limit of a day.

St. Petersburg is the easier family base. Its Gulf beaches have the gentle, shallow water small children need, and the resorts and condos are set up for families. Busch Gardens, the Florida Aquarium and the Clearwater Marine Aquarium are all within a drive, and Orlando is near enough for a long day.

Palm Beach is safe and calm but built for adults, and children can feel out of place in its formal restaurants. The zoo, the science centre and Manatee Lagoon are across the bridge. Peanut Island's shallow lagoon is a real treat for young swimmers.

Getting around is much the same in both: a walkable centre, a trolley loop, and a car for nearly everything else. The useful exceptions differ. From West Palm Beach a fast train runs to Fort Lauderdale and Miami, so Palm Beach's biggest day trip needs no car, and the island's Lake Trail is a pleasure by bike.

In St. Petersburg a rapid bus line runs from downtown to St. Pete Beach, which suits anyone who wants the sand without driving. The Pinellas Trail makes cycling practical in the cooler months.

Palm Beach is much the better place to shop. Worth Avenue is a true luxury street, with the major fashion houses and jewellers in Mizner's courtyards. Its consignment shops sell designer clothes from local wardrobes, and Antique Row across the water has furniture and decorative arts.

St. Petersburg has no luxury street. Its shopping is small and independent: vintage and record shops along Central Avenue, local glass and prints, and the Saturday Morning Market in winter. For brand names you drive to Tampa's malls.

Neither is cheap, but Palm Beach costs far more. Island hotels in winter are priced well above big-city levels and restaurants are aimed at a wealthy clientele. Many visitors stay in West Palm Beach and drive over to soften the bill.

St. Petersburg has the ordinary prices of an American beach resort, still more than most of Europe once tax and tips are added. Staying downtown, using the free beaches and parks and avoiding the February to April peak keep it manageable. Summer is cheaper in both, but you pay in heat and storms.

Palm Beach's arts life is grand and classical. It centres on the Kravis Center's winter season of touring Broadway musicals, ballet and visiting orchestras, and Palm Beach Opera stages its short season there too. The Society of the Four Arts adds chamber concerts and Palm Beach Dramaworks puts on serious plays, but from late spring the calendar thins sharply.

St. Petersburg is more informal. The Florida Orchestra plays the Mahaffey Theater on the waterfront, but the city's edge is rock and indie bands in an open-air courtyard and live sets in bars at weekends. For opera, ballet and the big Broadway tours, you cross to Tampa.

Palm Beach is the better place to unwind. The whole island is quiet and slow, and its large oceanfront resorts are built around polished spas, salt-water pools and fitness programmes. Beach yoga and early sea swims are easy to add.

St. Petersburg has fewer resort spas, mostly at the historic beach hotels, and its restfulness is simpler: sunset on the sand and the sleepy streets of Pass-a-Grille. Neither has a public bathing tradition, so in both, wellness means a day at a resort spa.