Colorado is the Rocky Mountains turned into a year-round family playground. In winter the resorts at Breckenridge, Beaver Creek, and Keystone run some of the best ski schools in the country alongside gentle beginner slopes, tubing hills, and ice rinks, so a first family ski trip rarely goes wrong. Come summer those same mountains swap skis for hiking, biking, and gondola rides, and Rocky Mountain National Park opens up with scenic drives, easy trails to alpine lakes, and herds of elk and bighorn sheep close enough to thrill a child. The altitude is the only thing to plan around; the scenery does the rest.

Beyond the peaks, the variety keeps coming. Denver offers a genuinely great run of family museums, a downtown aquarium, and a ballgame at Coors Field, while Colorado Springs delivers the towering red rocks of the Garden of the Gods and the drive up Pikes Peak. For pure delight, the Durango and Silverton steam train chuffs through canyons no road reaches, the Arkansas River gives older kids their first whitewater rafting, and the hot springs at Glenwood reward everyone at day's end. The accommodation runs from ski-in, ski-out mountain resorts to cozy cabins and lodges, many with pools, game rooms, and adventure programs. Colorado is for families who want real mountains and real altitude, in whichever season suits them.