Moab or San Diego?

There is no contest here. Moab is high desert far from any coast, and swimming there comes down to Mill Creek's shallow pools, Ken's Lake and cold, silty sandbars on the Colorado that call for care.

San Diego has a whole coastline to choose from: Coronado's wide strand, the boardwalk shared by Mission Beach and Pacific Beach, beginner surf at La Jolla Shores and quieter cliff-backed beaches up through Encinitas and Carlsbad. Expect a cool ocean outside late summer and morning cloud early in the season.

Moab feeds you well after a long day but rarely makes a meal the point. Main Street has burgers, tacos, pizza and brewpubs, choice thins in winter, and Utah's alcohol rules make a drink with dinner more formal than visitors expect.

San Diego has a real food identity, shaped by the border: Baja fish tacos, carne asada and the California burrito stuffed with fries, plus the Asian kitchens of Convoy Street and the restaurants of Little Italy. Both towns pour craft beer, but San Diego's brewing scene, from North Park to Miramar, is on another scale.

Moab's culture is on its cliffs rather than in its buildings. There are Ancestral Puebloan and Fremont petroglyphs along Potash Road and Kane Creek, dinosaur trackways and the small Museum of Moab, which together make a morning at most for anyone after indoor sights.

San Diego gives culture several days. Balboa Park's Spanish Colonial Revival buildings hold the art, natural history and air and space museums, the USS Midway and historic sailing ships line the waterfront, and Old Town and the first of California's missions tell the Spanish and Mexican story. It is solid rather than world class, but it fills a stay.

Moab goes to bed early. A few brewpubs and bars fill with mountain bikers and rafters, most of the town is asleep by eleven, and the best thing after dark is the deep, star-filled desert sky.

San Diego gives you a choice of evenings. There are rooftop bars and dance clubs in the Gaslamp Quarter, the student and surfer bar strip of Pacific Beach, and cocktail bars and taprooms in North Park and Hillcrest, which is also the centre of gay nightlife. It is sociable rather than famous, but it offers a proper night out where Moab offers a pint and an early start.

Both are outdoor places, but Moab is the exceptional one. Arches begins minutes from town, and Canyonlands' Island in the Sky and Dead Horse Point look over the canyons of the Colorado and Green rivers. The Slickrock Trail, the Whole Enchilada descent from the La Sals, river rafting and climbing at Wall Street draw people from around the world.

San Diego's strengths are variety and an easy climate. It has sea lions at La Jolla Cove, the bluffs of Torrey Pines, tide pools at Cabrillo, surf breaks and grey whales passing in winter, with pine forest and the Anza-Borrego desert inland. These are fine active days, but none matches the scale of Moab's canyon country.

Days out from Moab mostly mean more landscape and a few small towns: Green River, Monticello and the pioneer stone houses of Bluff. If you're willing to spend most of a day driving, you can reach the Ancestral Puebloan sites at Edge of the Cedars and Hovenweep.

San Diego's outings are far more varied, largely thanks to the border. Tijuana is a trolley ride and a walk away. A longer drive south reaches the vineyards of the Valle de Guadalupe, with the port of Ensenada beyond. Closer to home there are Temecula's wineries, the hill town of Julian and beach towns up the coast by train, and Los Angeles is about two hours away.

Moab works for active school-age children who love scrambling on rock. Short walks to Sand Dune Arch and the Windows, dinosaur tracks, gentle raft floats and Junior Ranger programmes all go down well. Heat, unfenced drops and hours in the car make it hard going with toddlers.

San Diego is one of the easiest family destinations anywhere. The zoo and Safari Park, SeaWorld, Legoland, the calm water of Mission Bay and the Birch Aquarium cover every age. Mild weather and relaxed restaurants keep the days simple, though each big park takes a full day of its own.

Both need a car, but Moab needs one more. Main Street is walkable and a paved path runs to the Arches entrance, but the parks and trailheads lie down long desert roads and dirt tracks with no public transport, so visitors without a car rely on outfitters' shuttles.

San Diego at least lets you manage part of a stay without one. The trolley links downtown, Little Italy, Old Town and the border, and coastal trains reach the beach towns. La Jolla, Legoland and the Safari Park are another matter, and beach parking is tight on summer weekends.

Moab sells what you need for the trail: bike, climbing and camping gear, rock shops full of geodes and fossils, and galleries with Southwestern art and Navajo jewellery and weavings. San Diego adds real browsing, with luxury brands at Fashion Valley, an outlet centre by the border, boutiques and vintage shops in Little Italy and North Park and Mexican crafts in Old Town, though nothing that would justify the trip on its own.

Neither is cheap, but Moab gives a careful traveller more ways to save. Its motels charge resort rates in spring and autumn, and rafting or jeep tours add up. Still, one national park entry covers a week, public and dispersed camping cost little, the best hikes are free and winter is much cheaper.

San Diego's costs are harder to avoid. Beach and downtown hotels are expensive, especially in summer, and the zoo, SeaWorld and Legoland all charge high admission. Taco shops, free beaches and Balboa Park's gardens help, but a week here usually costs more.

Moab's stage is essentially the Moab Music Festival at the end of summer, whose chamber concerts are sometimes held in canyon grottoes reached by boat. The rest of the year there is little beyond a weekend band in a brewpub. San Diego has a year-round programme built on theatre, with the Old Globe's open-air Shakespeare stage and the La Jolla Playhouse both sending shows to Broadway, plus the symphony's summer concerts on the bay and a short opera season.

Neither city has a bathing tradition, and Moab is the less restful of the two. Days start early and run long in the heat, and its spas amount to a few massage studios for sore legs. Its calm comes from quiet desert evenings and the cliffs turning red at sunset.

San Diego makes slowing down easier. It has resort spas in La Jolla, Coronado and Carlsbad, the long-standing yoga and meditation culture of Encinitas, and mild weather for unhurried walks along the shore.