Copper Mountain or Sun Valley?

Neither place is for swimmers, but Sun Valley at least has a summer lake shore. Copper Mountain's Summit County reservoirs are fed by snowmelt and used for boating, so swimming there means a heated pool. From Sun Valley you can drive about an hour to Redfish Lake under the Sawtooths, where there is real sand, though the water stays cold even in August.

Copper Mountain feeds you like a resort. You get burgers and chilli in the mid-mountain lodges, pizza and Mexican food in the village, and many visitors cook in their condos. For a better meal you drive to Frisco or Breckenridge.

Sun Valley eats noticeably better because Ketchum is next door. For such a small town it has a lot of restaurants, and the more ambitious kitchens cook Idaho trout, lamb and elk. Summer adds patio dining and a farmers' market.

Copper Mountain has nothing to see in the village itself. The Victorian mining heritage of the area belongs to Breckenridge and Leadville, so any sightseeing means getting in the car.

Sun Valley has a little more history of its own. The Union Pacific railroad built it in 1936 as America's first destination ski resort, the world's first chairlifts ran here, and the corridors of the lodge are still lined with photographs of film stars. Add Hemingway's grave in Ketchum and a small art museum and you have a pleasant afternoon, but not more.

Evenings in both places revolve around après-ski and end early. The difference is in the setting. At Copper Mountain the drinking happens in the bars at the lift base and on the village plaza, and anyone wanting a later night takes the half-hour trip to Breckenridge. Sun Valley's après-ski moves into Ketchum, where saloons, wine bars and a couple of old western bars feel more like a town night out, and some stay loud until closing.

Both are first-rate mountain destinations, but the skiing differs in kind. Copper Mountain has treeless bowls above 3,600m and terrain divided neatly by ability. Its real advantage is having neighbours: Vail and several other Summit County ski areas are close enough to try a different mountain each day, which Sun Valley's lone peak cannot match. In summer the Colorado Trail crosses the resort, a paved path climbs over Vail Pass, and fourteen-thousand-foot peaks are within an hour.

Sun Valley centres on Bald Mountain, whose long, steep runs drop straight down the fall line, with groomed Nordic trails and backcountry touring on top. Its summers offer more variety: dense singletrack, fly fishing on the Big Wood and at Silver Creek, rafting on the Salmon and the alpine lakes of the Sawtooths.

Copper Mountain is far better placed for outings. Breckenridge's Victorian main street, Leadville's silver-boom historic district and Vail's Alpine-style village are all within easy reach. Georgetown's narrow-gauge railway and Denver's museums are further down the interstate.

Sun Valley is surrounded by empty country. Apart from Hailey's short main street, the log-cabin outpost of Stanley and Shoshone Falls, about two hours south, most excursions lead into the mountains rather than to towns.

Copper Mountain is built more deliberately for children. The car-free village, the ski school, snow tubing, a mountain coaster and an indoor action-sports centre give you plenty to fall back on when legs tire. Sun Valley is safe and relaxed, with a separate beginners' hill, horse rides and an outdoor ice rink. Still, nothing there is made specifically for children, and a rainy day is hard to fill.

In both places the altitude needs watching with small children, especially in the first couple of days.

In both resorts you can get by without a car day to day, but the setup differs. At Copper Mountain, walkways, lifts and a free shuttle link the villages, and county buses run on to Frisco, Breckenridge and Keystone. Getting there, though, means about two hours from Denver on the I-70, which can be slow in winter.

Sun Valley has a small, walkable town grid, a free bus and a bike path down the valley, plus a small airport close by at Hailey. Once you leave the town, however, trailheads and hot springs are spread along long roads with no public transport.

At Copper Mountain, shopping is limited to ski rental, outdoor gear and resort-branded clothing. For more choice you go to the Silverthorne outlets or the boutiques in Breckenridge. Sun Valley offers a short but proper browse in Ketchum: fine art and western art galleries with evening gallery walks, well-stocked fly-fishing shops and upmarket boutiques selling cashmere and western wear.

Both are expensive, but Copper Mountain is somewhat easier on the wallet. It costs less than the grandest neighbouring resorts, and condos with kitchens and cheaper beds in Frisco or Silverthorne make a real difference. Sun Valley's prices are set by its wealthy second-home community, and there is little budget lodging anywhere in the valley. Coming in spring or autumn is the main way to save there.

Sun Valley clearly offers more in summer. A professional orchestra plays several weeks of free symphony and chamber concerts in a pavilion beside the lodge, and audiences picnic on the lawn. Star figure skaters perform on the outdoor rink on summer evenings. Copper Mountain has bands on the plaza on some summer weekends and acoustic sets at après-ski. For a real programme you have to drive to Breckenridge.

Sun Valley is the more restorative stay. The resort and larger hotels have full spas and outdoor heated pools, which are lovely under falling snow, and natural hot springs sit beside the creek in the Warm Springs valley. At Copper Mountain, relaxing means a hot tub facing the slopes or a massage at the athletic club, and the nearest hot springs are a long drive across the mountains.