Guanajuato or Mazatlan?

There is no contest here. Guanajuato is in the mountains, a long day's drive from either coast, so swimming means a hotel pool or a warm balneario in the countryside.

Mazatlan has sand along nearly its whole Pacific front, from the rocky coves at Olas Altas through the Zona Dorada hotel strip to the wide beach at Cerritos. Boats also run to Isla de la Piedra and the sheltered coves of Isla de Venados. The open beaches can have heavy surf, so weaker swimmers do better on the islands.

Mazatlan eats better, as long as you want seafood: aguachile, smoked marlin tacos and whole fish grilled over coals at beach shacks, with shrimp cocktails from carts in the morning. Guanajuato's cooking is plainer highland food, with enchiladas mineras, gorditas and the food counters of Mercado Hidalgo.

Neither is a fine-dining city, and both run short of variety after a few days. The difference is that Mazatlan does its one subject very well, while Guanajuato's best meals take some finding in the side alleys, away from the terraces on the Jardín de la Unión that trade on the view.

Guanajuato is the stronger cultural stop by a distance. The whole ravine town is a World Heritage site, with its painted houses, the baroque Templo de la Valenciana, the Teatro Juárez and the Alhóndiga de Granaditas, where the fighting of 1810 began. Diego Rivera's birthplace, the Quijote museum and the mummies add depth.

Mazatlan's old port quarter around the Plazuela Machado is attractive and worth an evening, and the cliff divers and El Faro lighthouse are fun to see. Its museums are small, though, and most visitors treat the centre as a break from the beach.

Mazatlan has more to go out for. The Zona Dorada's big open-fronted bars and dance clubs run late at weekends, the Plazuela Machado offers a calmer drink, and brass-heavy banda plays everywhere. Carnaval before Lent turns the malecón into a party that lasts most of a week.

Guanajuato's evenings are smaller and led by its students. People start on the terraces of the Jardín de la Unión and Plaza San Fernando, then move on to mezcal bars and a handful of clubs in the stone alleys, best from Thursday to Saturday. It is friendly, but not a reason to come.

Mazatlan's outdoors are on the water. You can kayak and snorkel around Isla de Venados, watch humpback whales in winter, fish for marlin, surf the point breaks at Olas Altas and see herons in the mangrove estuaries. Turtle hatchlings are released on nearby beaches in late summer and autumn.

Guanajuato offers dry hill walking instead: up to the Pípila, a half-day climb on La Bufa, oak forest trails in the Sierra de Santa Rosa and the view from Cristo Rey on the Cerro del Cubilete. It is rewarding for walkers, but there is less variety.

Guanajuato is the better base for outings. San Miguel de Allende is about an hour and a half away, Dolores Hidalgo with its Talavera workshops about an hour, and Querétaro, with its aqueduct and historic centre, about two. Add the half-abandoned mining town of Mineral de Pozos and small wineries, and a week of trips is easy.

From Mazatlan the choice is the villages of the Sierra Madre foothills: Concordia, Copala, El Rosario or Cosalá. They are charming but much like one another, and most visitors make one trip inland before going back to the coast.

Mazatlan is built around family vacations. It has the aquarium near the seafront, boat trips to calm island coves, hotel pools and kids' clubs in the Zona Dorada, and a malecón where children are part of every evening. It works for any age, as long as small swimmers stay off the surf beaches.

Guanajuato suits older children who like to walk. The funicular, the road tunnels and the singing callejoneadas go down well, and the mummies divide opinion. The stairways defeat pushchairs, though, and little is laid on for young children.

Guanajuato is compact. Almost every sight is a short walk from the Jardín de la Unión, traffic goes underground through tunnels, and a funicular climbs to the Pípila. The price is effort: steep lanes and stairways at about 2000m above sea level slow everyone down.

Mazatlan stretches along roughly 20km of coast, so getting between the old centre and the Zona Dorada means a bus, a taxi or an open-air pulmonía. The malecón makes a fine walk or bike ride when the heat allows.

Neither is a shopping destination, and the difference is in the souvenirs. Guanajuato leans to crafts: majolica-style ceramics, silver, wooden toys, Cervantes keepsakes and cajeta from Mercado Hidalgo, with León's leather and shoe trade about forty minutes away. Mazatlan's Zona Dorada sells hammocks, silver and beachwear, while the Pino Suárez market and ordinary malls cover everyday buying.

Both are good value, but Guanajuato is the cheaper of the two. Market meals, buses, taxis and museum entries cost little. Only the boutique hotels and the restaurants on the main plazas push up the bill, and rooms are scarce during the Cervantino in October.

Mazatlan is also priced for Mexican families, with cheap street seafood and buses. A beachfront room is the bigger expense, though, and rooms cost more at Carnaval, Easter and Christmas.

Guanajuato has the bigger stage. Each October the Festival Internacional Cervantino fills the Teatro Juárez, the plazas and the university courtyards with theatre, dance and orchestras. All year, groups of students in minstrel costume lead singing walks through the alleys most evenings, though outside October the formal programme is modest.

Mazatlan's centre for the arts is the restored Teatro Ángela Peralta, which hosts opera, concerts and an autumn festival. Day to day, live music means banda sinaloense at beach restaurants and along the malecón.

Neither has a bathing tradition of its own, and in both the spas are mostly in hotels, so the difference is in the kind of rest. From Guanajuato the best option is a half day at a thermal balneario such as Comanjilla near León, since the town itself is noisy at weekends with students and street music.

Mazatlan relaxes through the beach routine of hammocks, sunsets and walks on the malecón. The quietest stays are at Cerritos or on Isla de la Piedra, away from the music of the Zona Dorada.