Honolulu or San Diego?

Both cities live on their coasts, but the water decides it. Honolulu's Waikiki faces calm, reef-sheltered sea that is warm enough for a long swim in any month. The soft sand of Lanikai and Kailua, the snorkelling bowl of Hanauma Bay and the summer calm of the North Shore are all within an hour.

San Diego has more sand and more space, from Coronado's broad strand to the Pacific Beach boardwalk and the cliff-backed coves of Encinitas. But the Pacific here is cool, comfortable only late in summer and wetsuit water in winter. It is a beach city for walking, surfing and volleyball more than for lazy swims.

In both cities the best meals come from casual counters rather than famous kitchens. Honolulu's mix is the richer one. Kalua pig and poi, poke sold by weight, plate lunches and malasadas sit alongside Japanese cooking of real quality, and Kaimuki, Kapahulu and Chinatown are where you see how locals eat.

San Diego's strengths are narrower but distinct: Baja-style fish tacos, carne asada and the fries-stuffed California burrito. Its craft beer culture is something Honolulu cannot match, with taprooms clustered in North Park and Miramar, and Convoy Street adds a long run of Asian kitchens.

These two are close, and in both the serious sightseeing fits into two or three days. Honolulu's sights tell a story found nowhere else in the United States: Iolani Palace, the only royal residence on American soil, the Polynesian collections of the Bishop Museum, and the memorials at Pearl Harbor.

San Diego gathers its museums in one place, Balboa Park, where collections of art, natural history and aviation share Spanish Colonial Revival halls. Old Town and Mission San Diego de Alcalá cover the Spanish and Mexican past, and the USS Midway gives the waterfront its own naval history.

Neither is a city for late nights, and both wind down early. Honolulu's evenings centre on a sunset mai tai by the sand, with Chinatown's cocktail and dive bars for something more local.

San Diego splits into more distinct scenes. There are clubs and rooftop bars in the Gaslamp, a student bar strip in Pacific Beach, brewery taprooms in North Park, and Hillcrest at the centre of the city's gay nightlife.

Honolulu's landscape is more dramatic and closer at hand. The rainforest at Manoa Falls, the Diamond Head crater rim and the fluted Koolau cliffs are all minutes from the beach. The reefs add snorkelling with green sea turtles, which San Diego's colder water cannot offer.

San Diego makes up for it with range rather than drama. It has sandstone bluffs at Torrey Pines, sea lions at La Jolla Cove, pine forest in the Laguna Mountains and the canyons of the Anza-Borrego desert. Both see whales in winter: humpbacks off Oahu and grey whales off California.

San Diego has the clear advantage here. Crossing into Mexico, whether to Tijuana by trolley or further south to the Valle de Guadalupe vineyards, is an outing Honolulu cannot match. Temecula's wine country, the hill town of Julian and the coastal towns reached by train widen the choice further.

Honolulu is limited by its island. Haleiwa, Kailua, the Polynesian Cultural Center and the Byodo-In temple make one good loop of Oahu, and the neighbouring islands are better with an overnight stay than as a rushed day.

Honolulu is a gentle place to bring children. The reef-sheltered water is warm, Ala Moana and the Ko Olina lagoons are calm enough for small swimmers, and Hanauma Bay makes an easy first snorkel. Older children can climb Diamond Head or take a surf lesson. The long flight and the cost weigh more when you are paying for several people.

San Diego offers far more on dry land. Honolulu has a zoo and an aquarium at the Diamond Head end of Waikiki, but San Diego's zoo is in another league and fills a whole day, with a ride high over its canyons for when small legs give out. When the sea is too cool for children to stay in long, a science centre and a children's museum make good fallbacks, and Balboa Park has room to run around between museum visits. The catch is distance: the big attractions are far apart, so most days go to just one.

Beyond the centre, neither city is easy without your own transport, but Honolulu is the simpler of the two. Waikiki is flat and walkable from end to end, and TheBus reaches Pearl Harbor, Chinatown and the North Shore, so most visitors only need a car for a day or two to loop the island.

San Diego's walkable core is downtown, the Gaslamp and Little Italy, and the trolley and coastal trains handle some trips. La Jolla, the beaches and the big family parks are far apart, though, and most visitors end up hiring a car.

Honolulu is the stronger place to shop. Luxury fashion houses line Kalakaua Avenue, the Ala Moana Center is vast, and island goods such as koa bowls, Hawaiian quilts and ukuleles are worth seeking out.

San Diego is more about browsing. There is the open-air Fashion Valley mall, there are boutiques and vintage shops in North Park and Little Italy, galleries in La Jolla and Mexican crafts in Old Town, but no single street that draws serious shoppers.

Honolulu is the harder of the two on a budget. Nearly everything is shipped in, so hotel rooms, resort fees, drinks and car hire all cost more. Plate lunches, poke counters and the free beaches and hikes soften the bill.

San Diego is expensive as well, though a little easier on the wallet. Tickets for the family attractions and beach parking add up quickly, but taco shops, taprooms and the gardens of Balboa Park keep a day's spending down.

San Diego has the stronger stage. The Old Globe in Balboa Park and the La Jolla Playhouse are producing theatres that have sent shows to Broadway, and in summer the symphony plays outdoors on the bay.

Honolulu's offer is different and smaller. It centres on Hawaiian music and hula, from free shows at Kuhio Beach to slack-key guitar in hotel courtyards, with the restored Hawaii Theatre and short symphony and opera seasons for more formal evenings.

Neither city has a bathing tradition, so in both, rest comes from spas and a slower pace. Honolulu has lomilomi massage and dawn yoga on Waikiki's sand, with Kahala, Ko Olina or the windward side for real quiet. San Diego's calm is in Encinitas, with its long-standing yoga and meditation culture, and in the resort spas of La Jolla, Coronado and Carlsbad.