Durango, Colorado or Sun Valley?

Neither is a beach destination, and the water is cold in both. The difference is how close the water is. In Durango you can float the Animas on an inner tube right through town or swim at Lake Nighthorse on its edge. Sun Valley's best lake swimming is at Redfish Lake, an hour north under the Sawtooths, and the heated outdoor pools are the more dependable place for a swim near town.

Both eat like small mountain towns. The better kitchens cook trout, lamb and local produce, and neither offers much cooking from further afield. Durango has more character, with green-chile Southwestern plates and an unusual number of breweries whose taprooms fill with cyclists and rafters.

Ketchum's restaurants lean towards après-ski grills and pricier cooking with elk for second-home owners, with few cheap meals. Some kitchens also shorten their hours in spring and autumn.

Durango has more to see, though neither is a sightseeing town. Its railway heritage is still running, with steam engines leaving the 1880s depot and a roundhouse museum, all set among blocks of Victorian brick and sandstone. The college's Southwestern and Native American collection adds depth.

Sun Valley's story is more of a footnote: the lodge Union Pacific built in 1936 with the first chairlifts, and Hemingway's grave in Ketchum. A short afternoon covers it, and the town's galleries are the main thing to add.

Neither town stays up late, but Durango gives you more choice in the evening. Its brewery taprooms, patios along Main Avenue and Victorian saloons with a piano player are busy through the year, and students keep a few bars going at weekends. Ketchum's evenings follow the ski calendar: saloons and hotel lounges fill after the lifts close, then go very quiet once the season ends.

Both are first-rate mountain bases, with singletrack from the edge of town, good fly-fishing and golden aspens in autumn, so the choice comes down to the kind of mountain you want. Durango's San Juans are higher and wilder, with the Weminuche's peaks above 4,000m, the start of the Colorado Trail and whitewater running through the middle of town.

Sun Valley's strength is the ski mountain itself. Bald Mountain's long runs drop straight towards Ketchum, with dry snow and cold, sunny winters, while Durango's resort is half an hour away. In summer the Sawtooths, an hour north, add alpine lakes, climbing and rafting on the Salmon River.

This is the widest gap between them. From Durango you can reach Mesa Verde's cliff dwellings, ride the narrow-gauge steam train to Silverton, see the ancestral Puebloan ruins at Aztec and Chimney Rock, and soak at Pagosa Springs, all as day trips by car.

The country around Sun Valley is wilder and emptier. Hailey's short main street, the log-cabin outpost of Stanley and Shoshone Falls two hours south are about all there is, and most days out head into the mountains rather than to another town.

Both are safe, relaxed small towns for families who like the outdoors, and neither has a zoo or aquarium for a wet day. Durango has more to excite children in summer: the steam train up the canyon, gentle tubing on the river, the alpine coaster at the ski area and the ladders at Mesa Verde.

Sun Valley is at its best for a family ski week, with a separate beginner hill and a well-run ski school, plus horse rides and an outdoor ice rink in summer. Its deep midwinter cold is harder on toddlers, and teenagers who don't ski may find it quiet.

Sun Valley is easier to manage without a car, at least within the resort. A free bus links Ketchum, the village and the lift bases, so a ski week without driving is realistic.

Durango's compact Main Avenue and river trail are just as easy to walk. However, its ski area, trailheads and Mesa Verde lie along mountain highways, so you will want a hire car from the start. In both places, the wider region needs one.

Both offer a few blocks of browsing rather than real shopping, with outdoor gear and Western wear in each. The difference is in kind. Durango's distinctive buys are Navajo and Pueblo silver, turquoise and rugs, alongside sweet shops and souvenir stores. Ketchum leans upmarket, with fine and western art galleries, cashmere and home decor for second-home owners, and gallery walks on evenings in the main seasons.

Neither is cheap, but Durango is much easier on the wallet. Rooms are scarce in summer and at the peak of the ski season, and meals cost what they do anywhere in America. Even so, the trails and river are free, and spring and late autumn bring real savings.

In Sun Valley the wealthy second-home community sets the price of rooms, meals and lift access, and there is almost no budget lodging. Staying further down the valley and using the free buses helps, but it stays expensive in every season.

Both come alive only in summer, and both build their season around classical music, so the difference is one of style. Sun Valley's is the grander. A full professional orchestra plays free concerts in an open pavilion by the lodge while people picnic on the lawn, and star skaters perform on the outdoor rink.

Durango's summer is folksier, with a Victorian melodrama where the audience boos the villain and cowboy music over a chuckwagon supper. Its college concert hall also brings in touring acts at other times of year. Out of season, neither has much on most nights.

Hot springs are the draw in both, but in different forms. Durango's are more developed and easier to reach, with mineral pools a few minutes north of town and terraced pools at Pagosa Springs, plus more in Ouray, within a drive.

Sun Valley has full resort spas and heated outdoor pools that are lovely under falling snow. Its natural springs up the Warm Springs valley are rough pools beside the creek at the end of a dirt road. Neither has a bathing tradition, but both suit a quiet, unhurried stay.