San Diego or Miami?

Both cities are built around their coasts, and the water is what separates them. Miami's Atlantic is warm enough to swim in every month, and Miami Beach is one continuous strip of pale sand from the Art Deco front of South Beach to the calmer stretches at North Beach and Surfside, with Key Biscayne for shallow, sheltered water. The setting is flat and built-up, and sargassum can drift in during the warmer months.

San Diego's shoreline has more variety, from Coronado's wide strand and the Mission Beach boardwalk to the cliff-backed coves of Del Mar and Encinitas, and it is a real surf coast. But the Pacific there needs a wetsuit in winter and is only mildly warm by late summer, so it suits walking, surfing and paddling better than long swims.

Miami has the more distinctive food. Cuban cooking runs through the whole city, from ventanita coffee on Calle Ocho to lechon and croquetas, with Haitian, Venezuelan, Peruvian and Nicaraguan kitchens around it and stone crab and grouper on the seafood side. Brickell and the Design District add a chef-led upscale tier that San Diego mostly lacks.

San Diego eats more casually and leans on the border: Baja fish tacos, carne asada and the California burrito with fries inside. Its real speciality is craft beer, with taprooms across North Park and Miramar, and the Korean, Japanese and Vietnamese kitchens of Convoy Street give it an Asian range Miami cannot match.

Neither city is a museum destination, and a few days covers either one. Miami pulls ahead thanks to one striking ensemble, the pastel 1930s hotels of the Art Deco Historic District along Ocean Drive and Collins Avenue, backed by Vizcaya's gardens on the bay and the murals of Wynwood.

San Diego has more history to show, but it adds up to less. Balboa Park's exposition buildings hold most of the museums in one place, and the USS Midway, the adobes of Old Town and California's first mission tell the region's story without any single sight that matches South Beach's architecture.

This is the widest gap between the two. People travel to Miami for its nights out: big South Beach clubs with international DJs and bottle tables, downtown venues that run until dawn, warehouse parties in Wynwood and salsa on Calle Ocho. It takes money and stamina.

San Diego is an easy place for a drink, but nobody travels there for the nightlife. The Gaslamp Quarter and Pacific Beach supply the noise, North Park and Hillcrest suit cocktails and taprooms, and last call at 2am ends most nights around the time Miami's clubs fill up.

San Diego has the more varied outdoors, and a climate that allows it all year. Torrey Pines' sandstone bluffs, the sea caves and sea lions at La Jolla Cove and the tide pools at Cabrillo are all within the city, and about an hour inland the land climbs into the pine forest of the Cuyamaca and Laguna mountains, with the Anza-Borrego desert beyond.

Miami's landscape is flat and watery, and its great asset is the Everglades, with airboats, alligators and wading birds along the Anhinga Trail. Snorkelling over warm coral reefs in Biscayne National Park and off Key Largo is something San Diego cannot offer, but summer heat and mosquitoes leave winter as the only comfortable season.

San Diego has the more interesting outings, mostly because of the border. Tijuana is a trolley ride and a walk away, the Valle de Guadalupe wine country lies about two hours south, and Temecula's vineyards, the hill town of Julian and the North County beach towns by train fill other days.

From Miami the choice is thinner: Fort Lauderdale's canals, the Gilded Age mansions of Palm Beach and the seafood shacks of Key Largo and Islamorada. Key West is the famous one, but at three to four hours each way it really needs an overnight.

San Diego is one of the best cities anywhere to bring children. The zoo in Balboa Park, the Safari Park near Escondido, SeaWorld on Mission Bay and Legoland in Carlsbad could fill a week on their own, and the mild weather means outdoor plans rarely fall through.

Miami works for families mainly through its beaches, which are warm, calm and fine for swimming, with Zoo Miami, the Frost Science Museum and the Venetian Pool for other days. Summer heat, long drives and the party side of South Beach make it harder work, and the big theme parks are hours away in Orlando.

Both are car cities with a few walkable pockets, so in either one most visitors end up hiring a car or using ride-hailing. What differs is the transit you can use.

Miami has the free Metromover between downtown and Brickell, and South Beach is flat and easy to walk, but the Metrorail never reaches the beach. San Diego's trolley links downtown, Old Town and the Mexican border, and coastal trains run up to the North County beach towns, though La Jolla and the big parks still mean driving.

Miami is the city for serious shoppers. The fashion-house flagships of the Design District, the exclusive open-air mall at Bal Harbour and the huge Aventura Mall put it in a different class, with outlets on the western edge for bargains.

San Diego is better for browsing than for buying. Fashion Valley covers the luxury brands, while the independent and vintage shops of North Park and Little Italy, La Jolla's galleries and the Mexican pottery of Old Town have more local character than Miami's handful of cigar and guayabera shops.

Both are expensive, but the costs come from different places. In Miami the bill climbs through resort fees, parking and the price of drinks in South Beach clubs, while in San Diego it is admission to the zoo, SeaWorld and Legoland that adds up for a family. Both have cheap ways to eat, Cuban lunch counters in one and taco shops and taprooms in the other, and Miami's room rates drop in summer at the cost of heat and storms, whereas summer is San Diego's dearest season.

The two are evenly matched, but their strengths lie in different places. Miami leans towards dance and music: Miami City Ballet, the opera and touring shows at the Arsht Center, the New World Symphony in its Frank Gehry building, and Latin bands in Little Havana.

San Diego's strength is theatre, with the Old Globe and the La Jolla Playhouse both sending productions on to Broadway, and the symphony plays a summer season on its open-air stage by the bay. Miami's season is concentrated in winter, while much of San Diego's programme happens outdoors in summer.

Both rely on resort spas rather than a bathing tradition, though Miami Beach's long-established Russian and Turkish bath house comes closest to one. The real difference is pace. In Miami the social scene and loud South Beach nights work against rest, so finding calm means retreating to Key Biscayne or Surfside, while San Diego's beach towns, the yoga culture of Encinitas and the mild weather make slowing down come more naturally.