Los Cabos or San Diego?

Both coasts are the point of the trip, but Los Cabos has the warmer, clearer water for swimming. Medano Beach and the coves at Chileno and Santa Maria Bay on the Sea of Cortez side are calm and good for snorkelling. The catch is that the Pacific-facing beaches, Playa del Divorcio among them, are far too rough to go in.

San Diego has more shoreline and more variety. There is wide sand at Coronado, the boardwalk at Mission and Pacific Beach, gentle surf at La Jolla Shores and quiet cliff-backed beaches in North County. What holds it back is the water, which stays cool for much of the year and calls for a wetsuit in winter.

Both cities cook from the same Baja seafood tradition of fish and shrimp tacos, but San Diego offers more beyond that. Its craft breweries in North Park and Miramar, the Korean, Japanese and Vietnamese kitchens along Convoy Street, and late-night taco shops in every neighbourhood give you more range over a week.

Los Cabos eats best in San José del Cabo, at its taco stands, family kitchens and the farm restaurants in the hills, and the ceviche and aguachile are excellent. Around the Cabo San Lucas marina and in the resorts, meals tend to be expensive and generic.

San Diego gives a culture-minded visitor far more to do. Balboa Park alone holds a cluster of museums in its Spanish Colonial Revival buildings. The USS Midway, the adobes of Old Town and the first of California's missions add another day or two.

In Los Cabos the sights come down to San José del Cabo's small colonial centre, its mission church and the evening art walk through the gallery district. The arch at Land's End is scenery rather than history.

For a big, loud night out, Cabo San Lucas goes further. The streets behind the marina have large bars and dance clubs that run into the early hours, and the beach bars on Medano get going in the afternoon. It is all one kind of party, though, and San José and the resort corridor are quiet.

San Diego has more variety but less energy. There are rooftop bars and clubs in the Gaslamp, a student bar strip in Pacific Beach, cocktail bars and taprooms in North Park, and the gay scene in Hillcrest. Most of the city winds down early, so it suits an evening drink better than a late night.

Both are strong outdoor bases with the sea at the centre, and grey whales pass both coasts in winter. Los Cabos is about warm-water life: humpbacks off the cape, marlin fishing, diving, and the living coral reef at Cabo Pulmo up the East Cape. The Sierra de la Laguna offers serious hikes, although summer heat limits what you can do on land.

San Diego's outdoors works on land as well as at sea, and in every season. There are clifftop trails at Torrey Pines, sea lions and sea caves at La Jolla Cove, and tide pools at Cabrillo. Inland, the forests of Cuyamaca and the desert canyons of Anza-Borrego are both within a drive.

San Diego has the wider choice of outings. You can reach Tijuana by trolley, cross to the vineyards of the Valle de Guadalupe, visit Temecula's wine country or the hill town of Julian, and take the train to the beach towns up the coast. Los Angeles is also within reach.

From Los Cabos the list is short. Todos Santos is the best day out and La Paz makes a long one, and El Triunfo and Miraflores can be combined on a loop by car. Beyond them the peninsula is mostly desert.

San Diego is one of the easiest cities anywhere to visit with children. The zoo in Balboa Park and its Safari Park, SeaWorld on Mission Bay, Legoland in Carlsbad and the Birch Aquarium could fill a week, and the mild climate means plans rarely fall through. The main thing to plan around is the distance between them.

Los Cabos works for families mainly inside an all-inclusive resort with pools and a kids' club. Calm coves such as Chileno Bay and boat trips to see whales are easy wins, but there is no zoo, aquarium or theme park, and the Pacific surf needs watching.

Los Cabos is laid out as two small towns at either end of a 30km highway lined with resorts. The centres of San José del Cabo and the Cabo San Lucas marina are easy on foot, but most hotels sit out along the corridor, so taxis, shuttles or a hire car do the work. A car is also the practical way to reach Todos Santos or the East Cape.

San Diego lets you do more without one. Downtown, Little Italy and the waterfront are walkable, the trolley runs from them to Old Town and the border, and coastal trains reach the beach towns of North County. La Jolla, the Safari Park and Legoland are still far apart, though, so most visitors hire a car or use ride-hailing for those.

Neither city is worth the trip for its shops, but they fall short in different ways. Los Cabos sells mostly to people passing through from cruise ships and resorts, so the marina in Cabo San Lucas offers duty-free brands and souvenirs rather than anything worth hunting for. The exception is San José del Cabo, where galleries and Mexican folk art make an hour or two of wandering worthwhile and turn up the pieces most worth taking home.

San Diego comes out ahead because it is a large city that shops for itself, not just for visitors. In a day you can cover a big upmarket mall, bargain outlets near the border and a couple of neighbourhoods of independent and vintage shops, so there is far more choice in clothes and everyday buys. It offers range rather than character, though, and little of it would surprise someone who shops in other American cities.

Both are expensive, and neither suits a tight budget. In Los Cabos most of the cost comes from the corridor's luxury resorts, the marina restaurants and the taxis, so staying in San José del Cabo and eating at its taco stands helps. In San Diego you pay for hotels, tax and tip on every meal, parking, and high admission at the zoo, SeaWorld and Legoland, though the free beaches and Balboa Park's gardens help balance it.

San Diego has a real theatre scene. The Old Globe in Balboa Park and the La Jolla Playhouse produce serious work, the symphony plays summer concerts by the bay and the opera gives a short season. Los Cabos has little beyond cover bands, mariachi over dinner and resort shows, so anyone hoping for an evening of theatre or classical music should choose San Diego.

Los Cabos is the better place to switch off, as long as you stay in the right place. The corridor resorts compete on their spas, many with treatment rooms facing the sea, and several offer a temazcal sweat lodge ceremony. Cabo San Lucas itself is too noisy for a restful stay.

San Diego's version is less about pampering and more about a slower pace. There are resort spas in La Jolla, Coronado and Carlsbad and a long-standing yoga and meditation culture in Encinitas, and the mild climate suits unhurried walks along the coast.