Flagstaff or Keystone?

Neither is a swimming destination, but Flagstaff at least has a summer dip within reach. The creek pools of Oak Creek Canyon, Slide Rock among them, are a short drive towards Sedona, though they are cold, slippery and crowded at weekends.

At Keystone, Dillon Reservoir looks tempting below the resort, but it is fed by snowmelt and mostly closed to swimmers. Here the water means a hotel pool or a hot tub.

Flagstaff gives you more to choose from. Its strength is the cluster of craft breweries downtown and in the Southside, backed by a university-town mix of diners, Mexican and New Mexican kitchens and regional touches such as Navajo tacos and green chile.

Keystone eats like a resort: slopeside grills, après-ski burgers and a few more ambitious rooms, one reached by gondola. Elk, lamb and trout add some local character, but the range is narrow, and many visitors cook in their condo or drive to Frisco or Breckenridge.

There is a real gap here. Flagstaff's list is short but worth your time: the Lowell Observatory on Mars Hill, the Museum of Northern Arizona in the pines, the Arts and Crafts Riordan Mansion and a brick railroad-era downtown. That fills a day or two.

Keystone was built for skiing in the 1970s, and River Run Village is convenient rather than historic. The area's mining past survives only in the cabins and ruins up the Snake River valley, and for museums or old streets you have to leave the resort.

Flagstaff makes for the better evening out. Taprooms, cocktail bars and old Route 66 saloons sit a few minutes' walk apart downtown and in the Southside, and students liven up weekends in term time, although there are hardly any clubs.

Keystone's night peaks at après-ski on the River Run decks and is mostly over soon after dinner, because the resort fills with families and early risers. Anyone wanting more takes the bus to Breckenridge's Main Street.

Both are first-class mountain bases, but the landscapes are very different. Flagstaff looks out over a desert plateau and its canyons: one of the largest ponderosa forests in the world, the volcanic San Francisco Peaks, the lava flows of Sunset Crater, Sedona's red rock and the Grand Canyon, all under famously dark night skies.

Keystone is high alpine country built around skiing. It has its own three peaks with bowls above 3,600m, Arapahoe Basin next door and several big resorts within an hour. In summer the same slopes turn to lift-served biking, with Colorado's 14,000ft summits and the tundra of Loveland Pass close by.

The two are about level on day trips, but they reach back to different periods. Around Flagstaff the outings are ancient and scattered: Sinagua ruins at Walnut Canyon and Wupatki, the cliff dwellings of the Verde Valley, the Hopi mesas, plus Jerome and the railway from Williams to the canyon. All of them need a car.

From Keystone the theme is the 19th-century silver boom: Breckenridge, Georgetown with its loop railway, Leadville's opera house. Vail is close by, and Denver is within reach for a dose of city life.

Keystone is the easier choice with children, because the whole resort is set up for them. It has a large ski school, gentle runs, tubing, a snow fort and the skating rink at Lakeside Village, with free shuttles between condos and lifts.

Flagstaff suits curious children more than sporty ones. Telescope nights at Lowell, dinosaurs at the museum, rope courses and winter sledding all work well, but the outings are far apart, and long drives wear on young travellers.

Keystone is easier once you have arrived. Free shuttles link its three bases, and free county buses run to Dillon, Frisco and Breckenridge, so you can manage without a car. The catch is getting there: the drive or shuttle up I-70 from Denver can be slow in winter.

Flagstaff is easier to reach, with long-distance trains stopping downtown, and its centre is easy to walk or cycle. Beyond town, though, the mountain, the monuments, Sedona and the Grand Canyon all mean driving or booking a tour.

Flagstaff has the more interesting browsing. Navajo rugs, Hopi kachina carvings, pottery and turquoise jewellery are sold in downtown galleries, the museum shop and trading posts, and buying from established dealers is the way to be sure of authentic work. Keystone has mostly ski gear and rental shops, and its one real draw is the outlet centre in Silverthorne, ten minutes away, for brand-name clothes.

Flagstaff costs much less. Chain motels along Route 66 and brewery meals keep a stay reasonable, though a hire car, park entry fees and tipping add up, and rooms fill on summer weekends as the bed base for the Grand Canyon.

In ski season Keystone is expensive at every step: lift access, slopeside condos, equipment, ski school and resort meals. Free buses and self-catering from the Dillon and Silverthorne supermarkets soften the cost, and summer is gentler, but it never becomes cheap.

Flagstaff has the steadier year-round calendar. The Flagstaff Symphony and the university music school play on campus, and the restored Orpheum downtown hosts touring folk and indie acts.

Keystone's offer is concentrated in summer, with village-stage festivals, concerts at Dillon's amphitheatre by the reservoir and Breckenridge's classical festival. In winter the main venue is the professional theatre company in Silverthorne.

Neither has a bathing culture of its own, but they relax you in different ways. Keystone's version is recovery after skiing, with resort spas and a hot tub under falling snow at nearly every lodge, and natural hot springs over the pass at Idaho Springs. Flagstaff's version is pine air, cool evenings and bright stars in a slow town, and anyone wanting proper spa treatments drives an hour down to Sedona.