Every visitor to Yellowstone National Park wants to see the park's signature attraction, the Old Faithful geyser, which erupts about every 90 minutes. You can drive to Old Faithful on the Lower Loop Road from the park's west entrance and join the crowds of tourists sitting on benches waiting for this baby to blow. Another popular drive-up sight is the limestone terraces of Mammoth Hot Springs, near the north entrance, where masses of bacteria and algae in the thermal water turn the rocks orange, pink, yellow, green, and brown. But these two sights only scratch the surface of Yellowstone's geothermal features, if you're willing to get out and do some hiking to see them.
You'll have the geysers practically to yourself if you head for the Shoshone Geyser Basin, which begins a mile west of Shoshone Lake (find a trail head for Delacey Creek Trail on the road 8 miles east of Old Faithful; it leads 3 miles to Shoshone Lake). The North Shoshone Trail passes 26 campsites as it winds through a lodgepole-pine forest. The Bechler River Trail in the park's southwest corner is rich in waterfalls, cascades, and thermal areas. If its wildlife you're after, try the Sportsman Lake Trail, which passes through sagebrush plateaus full of elk and a meadow popular with moose.
Yellowstone is also one of the country's best places for families to go backpacking. Some beautiful campsites are just a couple miles off the road, and it only takes a walk of 20 minutes or so before you feel gloriously alone with the bison, elk, and other wildlife. Some great family trails for day hikes include these: at Mammoth, the 5-mile Beaver Ponds Loop from the hot springs at Liberty Cap (go in the evening or early morning to see the beavers); the 6-mile round-trip hike up Mount Washburn, an alpine trail leading to a 10,243-foot-high view over much of Yellowstone (watch for bighorn sheep); and the Clear Lake Trail from the Wapiti trail head, which wanders through beautiful rolling meadows to a strange body of water fed by hot springs.
The backcountry season here is short -- mid-June through the end of August, when the snow has finally melted off and streams drop to fordable levels -- so it's wise to make a campsite reservation way in advance.
Nearest Airport: Yellowstone, West Yellowstone, MT, 2 miles. Yellowstone Regional, Cody, WY, 52 miles.
Where to Stay: $ Madison Hotel, 139 Yellowstone Ave., West Yellowstone, MT (tel. 800/838-7745 or 406/646-7745; www.madisonhotelmotel.com). $$ Mammoth Hot Springs Hotel (tel. 866/439-7375 or 307/344-7311; www.travelyellowstone.com).
Best Time: June to September.