Big Sky or Keystone?

Neither is a swimming destination, and in both places the realistic way into the water is a hotel pool or a hot tub. What differs is the water you look at. In Big Sky it is the fast, rocky Gallatin River and a few small ponds. Keystone has the broad Dillon Reservoir below it, which is too cold and mostly closed for swimming but good for a day of sailing or paddleboarding.

Both offer hearty resort food at resort prices, with a narrow range: game and trout, pizza and local beer. Big Sky's restaurants are spread across Mountain Village, Town Center, Meadow Village and the roadhouses in the canyon, and some cut their hours between seasons. For real variety, Bozeman is an hour's drive.

Keystone makes it easier to eat outside the resort. Dillon, Frisco and Breckenridge are only a short drive away, and many condos have kitchens. Its standout meal is the dining room at the summit, reached by gondola, with Colorado lamb on the menu.

Both were built as ski resorts in the 1970s, and neither is a place to go sightseeing. Big Sky's one piece of heritage is the pair of log cabins at Crail Ranch in Meadow Village. Keystone has a little more history around it, in the mining-era ruins and cabins up the Snake River valley above Montezuma, but you still have to leave the resort to see it.

In both, the evening peaks at après-ski and fades soon after dinner. Big Sky has a little more character after dark: taverns in Town Center stay open a while, and the old saloons in the canyon have pool tables and a ranch-country crowd.

Keystone itself goes quiet early, as you would expect at a family resort. Its advantage is that Breckenridge's Main Street is a short bus ride away for anyone who wants a proper night out.

One huge mountain against a cluster of ski areas: that is the real choice here, and either is superb. Big Sky centres on Lone Peak at 3,403m, with steep high runs, then the Spanish Peaks and the Lee Metcalf Wilderness for summer hiking, fly fishing and rafting on the Gallatin, and Yellowstone's wildlife within a day out.

Keystone gives you more mountains to choose from. Arapahoe Basin is minutes away, and Breckenridge, Copper Mountain and Vail are all within an hour. In summer you can climb two 14,000ft peaks, Grays and Torreys, walk the alpine tundra at Loveland Pass, sail on the reservoir and ride a paved bike path between the towns.

Keystone has far more within easy reach. The Victorian centre of Breckenridge is half an hour away, the loop railway joins the silver towns of Georgetown and Silver Plume, and Leadville and Vail make good days out. Denver is about an hour and a half away for museums, though weekend I-70 traffic can stretch that.

From Big Sky, apart from Yellowstone, the outings are fewer and longer. Bozeman, with its dinosaur fossils at the Museum of the Rockies, is an hour away. The gold-rush boardwalks of Virginia City and Nevada City are around two hours.

Keystone is built around families. It has a skating lake, tubing, a snow fort and gentle lower slopes, and condos and free shuttles make the logistics easy. Away from the snow it has little else for children, and the altitude is hard on young ones there too.

Big Sky is good for outdoor families, especially in summer, when the base area has zip lines and ropes courses and the bison in Yellowstone are close. The long drives and the height of Mountain Village, about 2,300m, mean more planning than at Keystone.

Keystone is much easier to manage without a car. Free shuttles link its bases, and free county buses go to Dillon, Silverthorne, Frisco and Breckenridge. Getting there is the hard part: the drive up from Denver over I-70 can be slow and snowy.

Big Sky stretches along about 15km of road. A free bus runs between the villages, but a car is close to essential for anything beyond the resort, and winter driving through the canyon calls for good tyres.

Neither is a shopping destination, but Keystone has one real advantage: the large outlet centre in Silverthorne, ten minutes away, for brand-name clothes and outdoor wear. In Big Sky the most interesting finds are the Western boutiques and the galleries of wildlife art. Beyond those, it means an hour's drive to Bozeman.

In Big Sky the main way to cut costs is to stay further out, down the canyon or in Bozeman. That means a daily drive to the lifts and the trailheads.

Keystone lets you save without leaving. The buses are free, many condos have kitchens, and the supermarkets in Dillon and Silverthorne make self-catering simple. Summer is the cheaper season in both, but neither works on a tight budget.

For mountain resorts, both have a decent amount on, though at different times of year. Big Sky's season is concentrated in the resort itself: touring musicians, chamber music and theatre at the small performing arts centre in Meadow Village in winter, then free concerts on the lawn and a short classical festival in summer.

Keystone relies on its neighbours. Dillon's amphitheatre beside the reservoir and Breckenridge's classical festival fill the summer, and Silverthorne's professional theatre company stages plays and musicals year-round.

Big Sky has the edge for unwinding. The large lodges and resorts run full-service spas with massages for tired ski legs, and natural hot springs lie about an hour away towards Bozeman.

Keystone's version is simpler: an outdoor hot tub at nearly every lodge and condo complex, best with snow falling, plus resort spas. Natural hot springs mean a drive over the pass to Idaho Springs, and the resort is at its busiest in the Christmas and spring-break weeks.