San Pedro de Atacama or Vina del Mar?

San Pedro has no beach at all, only an hour floating in the dense, cool salt water of Laguna Cejar or the Baltinache pools, with no shade around you. It is a novelty rather than a beach day, and a lodge pool is the nearest thing to lounging by the water.

Viña del Mar is a proper beach resort, with a string of sandy bays from Caleta Abarca and Las Salinas to the broad, sociable sands of Reñaca. The Humboldt Current keeps the Pacific cold and the surf is often strong, so you sunbathe and take brief dips rather than swimming lazily. Even so, it is the only one of the two where a trip can revolve around the sand.

Viña del Mar eats considerably better. Its strength is Pacific seafood such as congrio, machas and locos, along with the empanada counters on the Concón road and crisp whites from the nearby Casablanca Valley. The centre itself is more ordinary resort fare.

In San Pedro, the Andean touches are the interest: llama, quinoa, chañar and rica-rica in a pisco sour. Still, a village of a few thousand people offers little range, and after a few nights the menus around Caracoles start to blur together.

Neither is a culture destination, but Viña del Mar offers somewhat more. The Fonck Museum, with its Easter Island moai and Rapa Nui collections, the Belle Époque palaces and the fine arts museum in the Quinta Vergara fill an afternoon. Valparaíso's UNESCO-listed hills are on the doorstep for anything deeper.

San Pedro's heritage is older and rougher: the cactus-wood ceiling of its adobe church, the Pukará de Quitor fortress on its hillside and the ancient round houses of Tulor. They fit into half a day by bike and give a human backdrop to the desert rather than making a reason to come.

This is one of the widest gaps between the two. In January and February Viña del Mar keeps Chilean hours: dinner after nine, bars filling at midnight and Reñaca's clubs going until dawn, with the Art Deco casino adding a touch of old glamour. Things go quiet outside that season, but Valparaíso's bars remain a short ride away.

San Pedro goes to bed early because the geyser tours leave before dawn. A night out there means a pisco sour by a fire pit and then a telescope under the desert sky.

San Pedro de Atacama is in another league. The Valle de la Luna, the flamingo pools of the Salar, the El Tatio geysers above 4,300m and the blue Miscanti and Miñiques lagoons beneath snowy volcanoes amount to some of South America's most remarkable scenery, with world-class stargazing on top. The one constant limit is altitude.

Viña's outdoors are gentler and closer to sea level. You get sea lions and pelicans on the rocks towards Concón, the protected dunes, surfing in a wetsuit and the palm-forest climb in La Campana. All of it is enjoyable, but none of it compares with the desert.

Viña del Mar is far better placed. Valparaíso, with its funiculars and Neruda's La Sebastiana, is a short metro ride away. The Casablanca wineries, Isla Negra, the villages of Zapallar and Santiago itself are all manageable in a day.

From San Pedro, nearly every outing is into the landscape rather than to another town. Toconao's white-stone bell tower, the old church at Chiu Chiu and the vast Chuquicamata copper mine are the few real destinations, and Uyuni is a multi-day journey, not a day trip.

Viña del Mar is the easier family choice. Chilean families have vacationed there for generations, Las Salinas and Caleta Abarca are calm enough for paddling, and the Quinta Vergara gives children room to run. There are no big attractions built for children, though.

San Pedro suits adventurous teenagers who can sandboard, float in a salt lagoon and look at Saturn through a telescope. For small children, the pre-dawn starts, long minibus rides, altitude above 4,000m and freezing mornings are hard going.

In San Pedro, walking covers the village and nothing more. No bus goes to anything you came to see. Each outing means a tour seat, a hire car or, for the closer valleys and ruins, a bicycle and more effort than you might expect. Plan the stay around booked excursions rather than free wandering.

Viña del Mar lets you do far more on your own. The beaches, gardens and shops of the centre are a short stroll apart, and the coastal metro makes Valparaíso as easy to reach as another part of town. Reñaca and Concón are a bus or taxi ride away, which is slow in high summer. You only need a car or a tour for the wine country, Isla Negra and La Campana.

Shopping is no draw in either place. Viña del Mar does have more of it, with Avenida Valparaíso, large malls carrying chains and craft stalls selling copper and lapis lazuli by the beaches. San Pedro offers only its craft market and the shops on Caracoles, where the useful buy is an alpaca or llama wool layer for the freezing dawn starts.

A stay in San Pedro costs more than in most of Chile, because everything is trucked across the desert. Almost every sight also needs a paid tour or a hire car, plus park entry, and even the simple adobe guesthouses are dear for what they offer. Set lunches, self-catering and cycling to the nearby valleys are the main ways to save.

In Viña del Mar, what you pay depends on the calendar. Sea-view rooms climb sharply in January, February and on long weekends. For the rest of the year the same rooms are much easier on a budget, and buses, the metro, set lunches and empanadas keep day-to-day spending modest, so Viña is the cheaper base of the two for most of the year.

Viña del Mar has one event known across the Spanish-speaking world: the February Song Festival in the Quinta Vergara amphitheatre. The Teatro Municipal stages concerts, ballet and theatre the rest of the year.

San Pedro has no stage life to speak of. You might hear panpipes and charango in a restaurant, and costumed troupes dance through the streets at the feast of San Pedro and San Pablo and at Carnival.

San Pedro has the better restorative experiences. The Termas de Puritama step down a reed-filled canyon at bath-warm temperatures, and the desert lodges offer spas and pools facing the volcanoes. The catch is the trip's own rhythm of early alarms and thin air, so build in rest days.

Viña del Mar has no thermal springs and a sea too cold to linger in, so treatments mean a hotel spa. Its calm comes from long promenade walks and Pacific sunsets outside the summer rush.