Alta, Utah or Keystone?

Neither is a place for swimming, and both leave you with a hotel pool or a hot tub. What differs is the water nearby. Alta's nearest is the Great Salt Lake, far down the valley and too shallow and salty for bathing. Keystone has Dillon Reservoir just below the resort, too cold for swimming but good for sailing and paddleboarding on a summer day.

Keystone gives you more choice at the table. Beyond the slopeside grills and pizza, there are a few more ambitious dining rooms, including one reached by gondola at the summit, plus Colorado lamb, elk and trout and plenty of local craft beer. Frisco, Dillon and Breckenridge are a short drive away when you want something different.

In Alta, meals mostly happen in your own lodge, often on half board at long communal tables, with cafeteria lunches on the mountain. Utah's liquor rules shape how drinks are served, and for variety you have to drive down the canyon to Salt Lake City, weather permitting.

There is little sightseeing in either, and you go to both for the mountains. Alta's history is the ski area itself. It is a silver-mining camp that became one of the oldest ski resorts in the West, with traces of the old mines still on the slopes. Keystone is a purpose-built 1970s resort, but older mining history is easy to reach: there are cabins and ruins above Montezuma and Victorian towns nearby. Museums at either mean a city, Salt Lake City or Denver.

Keystone has a bit more going on after the lifts close. The bars and decks at River Run fill with skiers in boots, and Breckenridge's Main Street, a short bus ride away, has a proper night out. Alta stops at a drink in the lodge bar and an early night, and its regulars wouldn't want it any other way. Anything livelier means the next resort down the road or the drive to Salt Lake City.

Both are outstanding mountain destinations, but the skiing differs. Alta is all about depth. Storms off the Great Salt Lake bring some of the driest, deepest powder in North America, the terrain is steep, and the backcountry touring is serious avalanche country. In summer, Albion Basin's wildflower meadows and the short walk to Cecret Lake are the highlights.

Keystone is about breadth. It has long groomed runs, trees and high bowls on its own three peaks, with Arapahoe Basin a few minutes away and Breckenridge, Copper Mountain and Vail within an hour. Summer adds two 14,000ft summits close by, lift-served mountain biking and sailing on Dillon Reservoir.

Keystone has the wider choice of days out. Within about an hour you can reach Breckenridge's Victorian centre, the silver towns of Georgetown and Silver Plume with their historic loop railway, Leadville's mining-boom streets and Vail, with Denver further off. Ski-weekend traffic on I-70 can slow any of these.

From Alta, Salt Lake City and Park City are the obvious outings, with Ogden beyond, and after that the list runs out. In winter, every plan depends on the single canyon road staying open.

Alta only suits a family where everyone skis. There are children's lessons and gentle terrain by the base, but no pools, museums or shops to fill a day off the slopes. A storm can keep everyone indoors while avalanche control goes on. Summer is easier, with gentle wildflower walks in Albion Basin that small legs can manage.

Keystone is the better family base by a wide margin, with much more for children around the skiing. In summer there are paddle boats and bike trails, though away from the snow there is not much else aimed at children. Both resorts sit at 2,600m to 2,800m, and that altitude can leave young children tired for the first day or two. Midwinter cold at either calls for proper kit.

Once you arrive, Keystone is easier without a car. Free shuttles link its bases, and free county buses run to Dillon, Frisco and Breckenridge, although the drive up from Denver over I-70 can be slow in winter.

Alta is closer to its airport, about 50km from Salt Lake City, and many lodges are ski-in, ski-out. Everything still depends on Little Cottonwood Canyon's one road, which jams on powder mornings and closes after storms. Outside the ski season you will need a car.

Keystone has the edge because of Silverthorne. The large outlet centre ten minutes away draws people across the county for branded clothing and outdoor wear, and River Run adds a few gift and clothing stores. Alta has ski rental and tuning shops and little else, so any real shopping means Park City or Salt Lake City.

Both are expensive in season, and neither suits a tight budget, but the costs add up in different ways. In Alta almost all the beds are in a handful of lodges, often with dinner included, so visitors watching costs stay in the Salt Lake valley and come up by bus each day. Its lift tickets are moderate by the standards of major American resorts.

Keystone gives you more ways to save. Condos come with kitchens, there are supermarkets close by in Dillon and Silverthorne, the buses are free, and summer is noticeably cheaper. The Christmas, New Year and spring-break weeks are the most expensive of all.

Keystone has a real live-music season, mostly in summer. There are outdoor festivals on the village stages, concerts at Dillon's amphitheatre by the reservoir and Breckenridge's long-running classical festival. Silverthorne's professional theatre company plays all year. Alta has no venue of any kind, so a concert or a play means an evening in Salt Lake City.

There is little between them here, and both offer the same kind of recovery after a day on the slopes: an outdoor hot tub in the snow, a massage, a sauna, and no thermal water of their own. Alta's lodge spas are small, and the bigger one is at the neighbouring resort. What it has is a tiny, still village where nothing in the evening keeps you from rest.

Keystone has more spa choice across its several bases, and natural hot springs are within reach, with Idaho Springs over the Continental Divide and Glenwood Springs a much longer drive west. The difference is the calendar. Keystone fills up over Christmas and the spring-break weeks, so if your main aim is to unwind, go at another time. Alta stays quiet all season.