San Diego or Santa Monica?

San Diego has the longer and more varied coastline. The choice runs from Coronado's broad, flat strand and the boardwalk crowd at Mission and Pacific Beach to the gentle surf at La Jolla Shores and the quieter cliff-backed beaches of North County. Mission Bay has sheltered water where small children can paddle safely.

Santa Monica is built around one very wide stretch of sand, with lifeguard towers and the pier in the middle. The more scenic coves are up the coast at Malibu and Point Dume. In both places the water is cool and early summer can bring grey mornings, though San Diego's sea is slightly warmer in late summer.

The two are about level, but they eat differently. San Diego's best food is casual and comes from across the border: Baja fish tacos, carne asada burritos and late-night taco shops. Convoy Street has a long run of Asian kitchens, and the craft breweries give the city its own drink.

Santa Monica eats more polished and more seasonal, with menus shaped by its farmers market, good brunch and solid Italian and Japanese restaurants. What it lacks is cheap immigrant cooking. For that, Los Angeles means a drive east, while in San Diego it is in every neighbourhood.

San Diego has more to see on its own doorstep. Balboa Park alone fills a day with art, natural history and air and space museums, and the waterfront has the aircraft carrier USS Midway and historic sailing ships. Old Town, the first of California's missions and Cabrillo's landing site add early history.

In Santa Monica itself there is little beyond the pier, with its carousel and the end of Route 66, and the galleries at Bergamot Station. The Getty Center and the Getty Villa are both a short drive away and are excellent. After those, though, you need a longer trip into Los Angeles.

San Diego has the livelier night out, mostly because it offers real choice. You can dance in the Gaslamp Quarter, join the younger beach crowd in Pacific Beach, or spend a slower evening in the taprooms and cocktail bars of North Park and Hillcrest. Hillcrest is also the city's gay district. Even so, outside those two loud areas the city goes to bed fairly early.

Santa Monica keeps to drinks rather than dancing. A typical evening is a sunset cocktail on a hotel rooftop near the Promenade, a pub on Main Street or a casual bar in Venice, and the streets are quiet well before the bars close. There are almost no clubs, so a night of dancing means a long taxi ride each way to Hollywood or West Hollywood.

Both are good bases for getting outdoors, but in different ways. San Diego's strength is wildlife by the sea: seals at La Jolla Cove, kayaking into the sea caves and the tide pools at Cabrillo. It also has a wider range of landscapes, with pine-forest hiking about an hour east and the Anza-Borrego desert beyond.

In Santa Monica the trails start almost at the edge of town, with canyon walks through Temescal and Topanga up to views over the bay. The 35km beach path is right there for cycling and skating.

There is little to choose between them, but the trips are very different. From San Diego you can go to another country. Tijuana is a trolley ride and a walk across the border, and the Valle de Guadalupe wineries lie further south. Temecula's vineyards and the mountain town of Julian are on the US side.

Santa Monica gives you all of Los Angeles, from the Huntington Library in Pasadena to Hollywood. Santa Barbara's mission and red-tiled centre are up the coast, and Catalina Island is a ferry ride away. In both places, traffic decides how much you see in a day.

This is where San Diego pulls furthest ahead. It has a world-class zoo, a safari park with giraffes and rhinos on open plains, SeaWorld and Legoland, plus the Birch Aquarium and a science centre for cooler days. The attractions are spread out, though, so each one usually takes a full day.

Santa Monica is pleasant with children, with lifeguarded sand, the small fairground and carousel on the pier and a little sea-life aquarium. Beyond that, the big days out mean a long drive to Universal Studios or Disneyland. Some families also find the visible homelessness around downtown unsettling.

Santa Monica is the easier place to get around. The beach, the pier, the Promenade and Main Street are all walkable, the beach path suits bikes and local buses cover the rest. The E Line light rail goes straight to downtown Los Angeles.

San Diego's compact downtown and its trolley to Old Town and the border work well. But La Jolla, the beaches, the Safari Park and Legoland are far apart, and the buses are slow. Most visitors end up hiring a car.

Santa Monica has the better shopping. The pedestrian Promenade has chains and flagship stores, Montana Avenue has upmarket boutiques and Abbot Kinney in Venice has design-led fashion. Rodeo Drive is close enough for luxury labels.

San Diego is mostly malls, with Fashion Valley for department stores and a large outlet centre by the border. Browsing is better in the independent shops of Little Italy and North Park and among the Mexican crafts in Old Town.

Neither is cheap, but San Diego costs less. Taco shops, brewery taprooms and the free gardens of Balboa Park keep everyday spending down. The big family attractions charge high admission, though, and that adds up quickly.

Santa Monica is expensive even for California, especially if you want a room near the ocean in summer. The beach, the trails and the cheap buses and light rail help, and staying a little inland lowers the room bill.

San Diego is the stronger choice for an evening out. The Old Globe in Balboa Park, with its open-air Shakespeare stage, and the La Jolla Playhouse are serious theatres that have sent shows to Broadway. The symphony plays a summer season on an outdoor stage by the bay.

Santa Monica's own programme is small: chamber music and dance at the Broad Stage, acoustic music in small venues and free summer concerts on the pier. The Hollywood Bowl and Walt Disney Concert Hall are excellent, but each means a long drive at rush hour.

The two are level here, and neither has thermal baths or a bathhouse tradition. San Diego's relaxation is spread along the coast, with resort spas in La Jolla, Coronado and Carlsbad and the yoga and meditation scene around the clifftop gardens in Encinitas.

In Santa Monica it is all close to your hotel: classes on the sand, juice bars, day spas and a morning run along the ocean. Watching the sunset over the bay is a daily habit for many.