Alta, Utah or Sun Valley?

Neither town has a beach, and swimming is a minor part of a stay in both. Sun Valley has a little more to offer. In July and August you can swim from the sandy shore of Redfish Lake under the Sawtooths, though the water stays cold, and there are reservoirs, river eddies on the Big Wood and heated outdoor pools.

Alta's summer swimming is limited to lodge pools and hot tubs. The Great Salt Lake below is not a lake people swim in.

In Alta, meals mostly happen in the lodge. Many guests eat set dinners at communal tables on half board and take lunch in slopeside cafeterias. It is solid fuel for skiing. For variety you drive down to Salt Lake City, if the canyon road allows.

Ketchum gives Sun Valley a real choice of places to eat for a town its size. You'll find après-ski grills and pizza, a few ambitious kitchens cooking Idaho trout, lamb and elk, busy breakfast spots, and a farmers' market and patio dining in summer. Cheap options are scarce, and some kitchens cut back their hours in spring and autumn.

There isn't much to see in either place, but Sun Valley has a story you can actually visit. The railroad built the resort in 1936 as America's first destination ski resort. The lodge's corridors are lined with photos of film stars, and Hemingway's grave and memorial are in Ketchum. A history museum and an art museum will fill an afternoon.

Alta's past as a silver-mining camp shows only in old mine workings on the slopes. There are no buildings or museums to tour.

Evenings in Alta end with a drink in the lodge bar and an early night, and regulars like it that way. Sun Valley isn't a party town either, but Ketchum has saloons, wine bars and a couple of old western bars that stay loud until closing, with a band on busy winter weekends. The difference is between having one drink and going out for the evening, and you won't find a club in either town.

Both are outstanding mountain destinations, and the difference is in kind. Alta is about the snow itself. It sits at around 2,600m and often gets well over 12m of powder in a winter, the terrain is steep, the mountain is for skiers only, and backcountry touring in avalanche terrain is serious. In summer, the wildflower meadows of Albion Basin and the walk to Cecret Lake are the highlights.

Sun Valley has more variety. Bald Mountain's long runs drop straight down the fall line, and there is groomed Nordic skiing in the side valleys. In summer you get dense singletrack, fly fishing on Silver Creek, alpine lakes and climbing in the Sawtooths, and rafting on the Salmon River. Alta has none of that water.

Alta is the better base for days away, because a real city is close. Salt Lake City, with Temple Square, the State Capitol and its museums, is under an hour down the canyon. Park City's old mining Main Street and Ogden's railway street are also within reach. In winter, though, every trip depends on a single road that closes after storms.

Sun Valley is surrounded by wild country. Hailey's small main street and the log-cabin outpost of Stanley are pleasant, Shoshone Falls is about two hours away, and Boise is too far for a comfortable day. Outings here head into the mountains rather than to other towns.

Sun Valley is the easier choice with children. Beginners learn on their own gentle hill away from the main mountain, and in summer there are bike paths, an outdoor ice rink, horse rides and pools. Ketchum is quiet and simple to get around with a pushchair.

Alta has a ski school and beginner terrain right by the lodges, but nothing for a child who doesn't ski. Storm days can also keep everyone indoors during avalanche control. In both places, the altitude and the winter cold are hard on toddlers.

Sun Valley is easier to get around once you arrive. Ketchum is flat and walkable, a free bus links the town, the village and both lift bases, and a paved bike path runs down the valley. Many visitors spend a whole ski week without a car. Reaching it is harder: the local airport in Hailey is small, and the bigger airports are a long drive away.

Alta is the reverse. Salt Lake City's airport is only about 50km away, and many lodges are ski-in, ski-out. But the one road up Little Cottonwood Canyon jams on powder mornings and closes after storms, and you'll need a car outside the ski season.

Sun Valley clearly wins here. A few blocks of Ketchum hold fine-art and western-art galleries, good fly-fishing and outdoor gear shops, and boutiques selling cashmere and western wear, with gallery walks in the main seasons.

Alta has ski rental and tuning shops and a few racks of branded gear, and that's all. Real shopping means a trip to Park City or Salt Lake City.

Both are expensive, and staying up the mountain costs about the same in either. The way to save differs. At Alta, most beds are in a handful of lodges whose rates include dinner, but lift tickets are moderate and you can stay cheaply in the Salt Lake valley and come up by bus.

In Sun Valley, a wealthy second-home community sets the prices for rooms, meals and lifts. The savings are smaller: stay further down the valley, come in spring or autumn and use the free buses.

Sun Valley has a real summer season, and Alta has nothing at all. For several weeks a professional orchestra plays free symphony and chamber concerts in an open-sided pavilion by the lodge, with picnics on the lawn. Star figure skaters also perform on the outdoor rink in summer, a tradition from the resort's early years.

In Alta, a play or a concert means driving to Salt Lake City.

Sun Valley offers more ways to unwind. The resort and the larger hotels have full spas and steaming heated pools. Up the Warm Springs valley, rough natural hot springs pool beside a creek at the end of a dirt road.

Alta's wellness is mostly a hot tub in the snow, a sauna and a massage in a small lodge spa. What it does offer is deep quiet. On storm days the canyon is completely still, and nothing keeps you up at night.