Huatulco or Zihuatanejo?

The two are evenly matched on beaches, but the layout is different. Huatulco gives you nine bays along about 35km of coast, mostly small golden coves between rocky headlands. Boats hop between them in a morning, and Cacaluta and El Órgano have no road at all, so a beach day often means a boat trip.

Zihuatanejo is one deep bay. Most people base themselves on the long, calm crescent of La Ropa and take a water taxi to Las Gatas, where the old stone reef keeps the water flat for snorkelling. Ixtapa adds long open beaches and the calm coves of Isla Ixtapa. In both places the open-ocean beaches have rough surf.

Neither is a place to book for the food, but Zihuatanejo eats slightly better and is more firmly about the sea. Fish comes as tiritas cured in lime or split and grilled at the palapas on La Ropa and Las Gatas, and on Thursdays the whole town sits down to pozole.

Huatulco's appeal is Oaxacan cooking brought to the coast: mole, tlayudas, tamales in banana leaf, with mezcal and coffee from the hills. For the best of it, go to La Crucecita's market and the fondas around the square, not the resort buffets in Tangolunda.

Sights are thin in both, and either can be covered in a morning. Huatulco's are scattered: the Virgin painted across the dome of La Crucecita's church, and the Copalita park, where a small ceremonial site leads on to a forest walk to a clifftop. In Zihuatanejo the culture is mostly the fishing town itself, its whitewashed grid and pier, plus a small coastal archaeology museum on the waterfront.

Both are quiet places at night, and Zihuatanejo has only a little more going on. Its town evenings are sunset drinks and small bars full of locals and long-stay visitors, but Ixtapa up the road has louder beach bars and a few clubs that fill up in high season.

Huatulco's evenings centre on La Crucecita's plaza and its mezcal bars, with a few marina bars in Santa Cruz. Most nights the town is asleep by midnight. People who want to party go up the coast to Zipolite.

Huatulco has the stronger natural setting. A national park protects the coast from dry forest down to the coral patches, and boat trips pass blowholes and sea arches. Inland there is rafting on the Copalita, waterfalls at Llano Grande and shade-grown coffee farms around Pluma Hidalgo.

Zihuatanejo's outdoor life is mostly on the water: sport fishing for sailfish and marlin, snorkelling at Las Gatas and Isla Ixtapa, and paddling in the calm bay. On land, the lagoon at Barra de Potosí is full of herons and spoonbills and there are crocodiles in the mangroves, but hiking is limited. You can watch for humpback whales in winter from either town.

Huatulco has much better day trips. About an hour west lies a string of very different villages: Mazunte with its turtle centre, laid-back San Agustinillo, the fishing harbour at Puerto Ángel and bohemian Zipolite. The surf town of Puerto Escondido is within reach, and the coffee villages make a slow half day.

From Zihuatanejo the outings are smaller: a beach day in the surf village of Troncones, lunch on the sand at Barra de Potosí, or the ball court at Xihuacan. Neither town is close enough to a big city for a day out. Oaxaca and Acapulco both need an overnight stay.

Families will find the two much alike: calm coves, resorts with kids' clubs, small towns that are easy to manage, and nothing like a zoo or theme park. Huatulco's highlight is La Entrega, where children can snorkel over coral close to shore. Zihuatanejo has more small outings for when the beach gets dull: crocodile spotting in the lagoons, turtle releases in season and the boat ride to Isla Ixtapa.

Zihuatanejo is easier to get around. The centre is walkable, a waterfront path leads to Playa Madera, and local buses and colectivos run to La Ropa and Ixtapa, so most visitors never need a car. The hills between beaches are steep and often have no pavement, though.

Huatulco is spread across several bays. You can walk from La Crucecita down to Santa Cruz, but Tangolunda, Chahué and Maguey usually mean a taxi, the remoter coves need a boat, and a hire car is worth having for the coast villages and the coffee hills.

Shopping is minor in both, enough for souvenirs and little more, but the crafts differ. Huatulco's stalls sell Oaxacan crafts, such as embroidered blouses, black pottery and alebrijes, along with mezcal and local coffee. Zihuatanejo's artisans' market brings in silver from Taxco and lacquerware from Olinalá, and a few boutiques and Ixtapa's small plaza give it a slight edge for resort wear.

Zihuatanejo is the cheaper of the two, mainly because daily life there costs so little. If you stay in town, eat at taquerías and palapas and take the bus, your money lasts well. Prices rise in the boutique hotels above La Ropa and in Ixtapa.

Huatulco can also be cheap if you base yourself in La Crucecita and eat at the market. Because the bays are spread out, though, you pay more often for taxis and boat tours, and the all-inclusive resorts in Tangolunda push costs up.

Neither town is somewhere to plan evenings around performances, though Zihuatanejo has a little more. Its long-running international guitar festival brings concerts to the beach once a year, and in high season trova singers and mariachis play in restaurants. In Huatulco there are folk dance shows at the resorts and music on the plaza during local festivals.

Both are good places to slow down, and in both the slow pace does most of the work. Huatulco has the more established spa offer: full spas at the Tangolunda and Conejos resorts, and the temazcal steam bath run with herbs and a guide at several eco-centres. In Zihuatanejo, rest mostly means reading in the shade between swims. Its spas are in the hotels on the hills above La Ropa, and yoga is a bit easier to find than in Huatulco.