Napa or Santa Monica?

This is the widest gap between the two. Napa is inland and its coast is more than an hour away, too cold and rough for swimming, so summer swimming means a resort pool or the reservoir at Lake Berryessa.

Santa Monica is built around its beach: broad pale sand, lifeguard towers and the pier, with quieter, more scenic coves towards Zuma and Point Dume. The water is cool, though, and many people paddle rather than swim.

Napa is the stronger place to eat, because its food comes with the wine. In one day you can taste Cabernet at estates on the Silverado Trail and Pinot and sparkling wine in Carneros, then have dinner at one of the nationally famous tables in Yountville or St Helena. The Oxbow Public Market covers simpler meals.

Santa Monica eats well rather than memorably. The Wednesday farmers market supplies good seasonal Californian kitchens, seafood and brunch, but there is no wine country on the doorstep. Both share the same gap at the cheap end. In Napa that means the taquerias, and from Santa Monica it means a long drive east for the taco trucks of Los Angeles.

Neither is a sightseeing destination, but Santa Monica gives a culture-minded visitor more. It has the pier with its carousel and Route 66 sign and the galleries at Bergamot Station. Above all, it has the Getty Center and the Getty Villa a short drive away, and both hold serious collections.

Napa's interest lies in its period buildings: the 1880 Opera House on First Street, old stone wineries and the main streets of St Helena and Calistoga, with contemporary art at di Rosa. A day covers it.

Santa Monica has more of an evening out, though neither town has clubs. Rooftop bars over the ocean around the Third Street Promenade, pubs on Main Street and the more relaxed bars of Venice keep things going until a reasonable hour.

In Napa, a night out means a long dinner and a glass at a downtown wine bar, and the valley is asleep soon after. Anyone after a late night has to travel, to San Francisco from Napa and to Hollywood from Santa Monica.

Both have fine landscapes, but Santa Monica is the better base for getting outdoors. The Santa Monica Mountains start right behind the town, with trails in Topanga and Temescal Canyon. The beach path runs about 35km along the sand, and surf lessons and winter whale-watching add the sea.

Napa's outdoors is more about scenery than activity: dawn balloon flights over the vineyards, a cycle trail along the flat valley floor, redwoods in Bothe-Napa Valley State Park and the climb up Mount St Helena. Hot summer afternoons push walks into the early morning.

Napa has the better range of trips within easy reach. Yountville, St Helena, Calistoga and Sonoma are each a short drive, Healdsburg and the Russian River valley make a second wine region, and San Francisco is about an hour away by car or by ferry from Vallejo.

Santa Monica's options are varied but further away. Santa Barbara and Laguna Beach are about two hours' drive, Catalina is reached by ferry, and Pasadena and Hollywood are across Los Angeles. Traffic decides how far you get.

In Napa a child's day mostly follows the adults' plans: time in the car between cellars, waiting while the grown-ups taste, then an afternoon in the hotel pool. Anything aimed at children has to be sought out as a separate outing, such as the geyser at Calistoga or the animal park down the road in Vallejo. The valley is peaceful and safe, but children come along as guests rather than as the point of the trip.

Santa Monica turns that around. A family can spend a whole day on foot from the hotel, with sandcastles by a lifeguard tower in the morning and the Ferris wheel over the water in the afternoon, and nobody needs to sit in a car seat. The mild winters suit school breaks at any time of year, which Napa's cold, wet months do not. Only the big theme parks across Los Angeles call for a long drive.

Santa Monica is easier without a car. Its centre, the pier and Main Street are walkable, blue buses cover the town and the E Line light rail reaches downtown Los Angeles. The Getty and Malibu still need a car or ride-hailing.

Napa's compact downtown is easy on foot, but the wineries are spread along some 50km of road and the buses run too rarely to rely on. Since tasting and driving do not mix, most visitors hire a driver or join a tour.

Santa Monica has more to browse. There are chains on the Third Street Promenade, boutiques on Montana Avenue, surf shops on Main Street and design stores on Abbot Kinney in Venice, with Rodeo Drive nearby for luxury labels.

In Napa, the main purchase is wine, often shipped home by the case. Beyond that there are food gifts at the Oxbow Public Market, cookware and gift shops in St Helena and an outlet mall, but fashion barely features.

Both are expensive, and the difference lies in where the money goes. In Napa it goes on luxury resorts, estate tastings, special-occasion restaurants and a driver for the tasting day. You can save by staying in chain hotels further south, eating at taquerias and choosing smaller cellars.

In Santa Monica the big costs are oceanfront hotels, high restaurant bills and parking. On the other hand, the beach, the pier, the trails and the bike path are free and public transport is cheap, so an ordinary day out costs less than a day of tastings.

Santa Monica has a little more on its own stages and far more within reach. The Broad Stage puts on chamber music, dance and theatre, there is a long-running folk and acoustic scene, and the pier has free summer concerts. The Hollywood Bowl and Walt Disney Concert Hall are worth the long drive.

Napa's programme centres on the 1880 Opera House and an Art Deco theatre for touring acts. It also has a summer classical festival in winery venues and a large spring rock and pop festival at the fairgrounds. Outside those, a good evening means the trip to San Francisco.

Napa is the more restful stay. People have come to Calistoga's hot springs since the nineteenth century, and its mud baths and mineral pools sit alongside large resort spas that use vineyard products. Days in the valley are slow by design.

Wellness in Santa Monica is more active: yoga on the sand, runs along the ocean, juice bars and day spas, with sunset over the bay to end the day. It has no springs or bathing culture to match Calistoga.