Boulder or Flagstaff?

Neither town is anywhere near a coast, so a beach vacation is out in both. The difference is where you swim on a hot day. In Boulder it is in town: the sandy swim area at the reservoir or a float down Boulder Creek on an inner tube. In Flagstaff you drive down into Oak Creek Canyon for the cold, slippery pools at Slide Rock, which get crowded at weekends.

Boulder eats better. Its cooking is seasonal and health-minded, with plenty of vegetarian and vegan food, good bakeries, and a Saturday farmers' market by the creek that doubles as a social occasion. The hand-carved Dushanbe Teahouse is a lovely place for lunch, and Denver is close by when you want more variety.

Flagstaff is simpler: diners, burgers, barbecue and Mexican and New Mexican cooking, with Navajo tacos and green chile adding some local flavour. Both towns pour excellent craft beer, so for drinking there is little between them. The difference is on the plate.

Flagstaff has more to see. The Lowell Observatory, where Pluto was discovered in 1930, offers historic telescopes and night viewings, and the Museum of Northern Arizona holds a serious collection of Hopi, Navajo and Zuni art. The Riordan Mansion and the railroad-era brick downtown on Route 66 fill out a day or two.

Boulder's sights are about atmosphere rather than collections. You have the wooden Chautauqua colony beneath the Flatirons, the sandstone and red-tile campus, and I.M. Pei's atmospheric research laboratory on the mesa. Pleasant as they are, one day covers all of it.

Evenings in both towns centre on brewery taprooms and finish early, because so many people are up at dawn for the trails. Boulder's going-out is split between the bars around Pearl Street and the loud student strip on University Hill. For a real night out, Denver is about 40 minutes away.

Flagstaff's version is a short walk around downtown and the Southside, with old Route 66 saloons mixed in among the taprooms. The setting has more character, but there is no bigger city nearby for a late night.

These are two of the best outdoor bases in the American West, but the landscapes are very different. Boulder's draw is the Flatirons right behind town, a ring of protected open space with trails starting from Chautauqua, world-class rock climbing in Eldorado Canyon and canyon roads that serious cyclists come to train on. Rocky Mountain National Park is about an hour away.

Flagstaff brings volcanic country and the desert edge. There are alpine trails on the San Francisco Peaks, a huge ponderosa forest, and the lava flows at Sunset Crater. Sedona's red rock and the Grand Canyon's South Rim are both within a short drive, and the dark skies make stargazing part of the trip.

Day trips from the two towns are fairly evenly matched, but they take you to different things. From Boulder, the main outing is Denver by express bus, for its art museum, state capitol and Union Station. With a car you can add the old silver-mining towns of Georgetown and Idaho Springs or a relaxed afternoon in Fort Collins.

Flagstaff has no city nearby, but the scattered list goes deeper into history. There are the Sinagua ruins at Walnut Canyon and Wupatki, the cliff dwellings of the Verde Valley, hillside Jerome, the historic railway from Williams and the Hopi mesas. All of them need a car.

Both are safe, relaxed towns for children who like being outdoors, so the choice comes down to what they enjoy. Boulder has summer fun close at hand: tubing on the creek, the reservoir swim beach, gentle trails at Chautauqua and street performers on Pearl Street. Denver's zoo and aquarium are nearby for a bigger day out.

Flagstaff appeals to young stargazers and dinosaur fans, and in winter it adds sledding and snow play, while the steam-era train to the Grand Canyon is a treat in itself. It sits higher, though, so small children feel the altitude more for the first day or two, and the drives between outings are longer.

Boulder is much easier without a car. Downtown, the university and Chautauqua are all within a walk or short ride of each other, and off-street bike paths with underpasses run along the creeks. An express bus goes to Denver and its airport links. You only need to hire a car for trailheads and parks beyond the city limits.

In Flagstaff, only the compact downtown and Southside work well on foot. The motels are spread along Route 66, and the mountain, the monuments, Sedona and the Grand Canyon are all beyond any useful bus. Most visitors drive or book tours, and winter ice can make the mountain roads difficult.

Boulder has more to browse. The brick-paved Pearl Street Mall is lined with independent bookshops, galleries and boutiques, and the climbing, running and cycling shops are unusually good for a town of its size.

Flagstaff's strength is narrower but more distinctive: Navajo rugs, Hopi kachina carvings, pottery, and silver and turquoise jewellery. You find these in downtown galleries, the museum shop and trading posts, and it is worth buying from established dealers or directly from the artists.

Boulder is the dearer stay of the two, and timing matters. Hotel rooms are few for such a wealthy town, so prices peak in summer and again on university graduation and football weekends, when families and fans fill the town. Eating out comes at affluent American prices with tips on top, and the usual way to soften the bill is to sleep in Denver or a neighbouring town and drive in.

Flagstaff costs less to stay in, though some of the saving goes on the road. Rooms jump on summer weekends and in school breaks, when the town becomes the main bed base for the Grand Canyon, yet staying here is usually still much cheaper than staying in Sedona or at the canyon rim. Budget too for a hire car, fuel and national park and monument fees, since almost every outing here means a drive.

Boulder has the richer music scene. Small downtown rooms book touring rock and bluegrass most nights, and in summer the 1898 Chautauqua Auditorium hosts the Colorado Music Festival while Shakespeare is performed outdoors on campus. Red Rocks Amphitheatre is within easy reach.

Flagstaff's calendar is modest but steady. The local symphony plays in the campus concert hall, the restored Orpheum hosts folk and indie acts, and community theatre and outdoor summer concerts fill the gaps. It is a nice extra for an evening rather than a reason to visit.

Boulder is the better place for a restful stay. Its yoga and meditation culture has real roots, massage and acupuncture are easy to find, and the spring-fed pool at Eldorado Springs makes a gentle summer outing. For proper hot springs, Idaho Springs is an hour away.

Flagstaff's calm comes from the place itself: cool evenings, the smell of pine and bright stars. There are very few spas, so anyone looking for treatments or retreats heads to Sedona. Its higher altitude can also disturb sleep for the first night or two.