Mammoth Hot Springs Hotel
Land in Bozeman, Montana, and rent a car for the 90-minute drive through aptly named Paradise Valley. Stop for dream catchers and wolf T-shirts in the tchotchke mecca of Gardiner, then snap a photo at the Roosevelt Arch, built in 1903 by park promoters who thought the local scenery was too dull. Mammoth Hot Springs Hotel is in Mammoth Village, a 10-minute drive past the park's north entrance. You couldn't avoid it if you tried.
Hearing wolves from the park's Quadrant pack howling during a short night hike on Beaver Ponds Trail—a sound earnestly and poorly imitated several beers later in the hotel's art deco bar.
Sitting through the 30-year-old flick The Challenge of Yellowstone in the Albright Visitor Center, fearing that the grandeur-thumping, 25-minute PSA might never end. It makes Ken Burns's 12-hour national park series feel like a YouTube video.
The Mammoth area's resident elk herd—especially during the rut, from late September to early October. The herd's massive, aggressive, six-pointed patriarch, "Number 6," died last year trying to hop a fence. The resulting power vacuum could make for epic antler clashes among this year's class of randy bulls.
Last year, the four-wolf Canyon pack migrated 30 miles from its territory near the Grand Canyon of the Yellowstone to den just east of Mammoth—the closest den to any of the park's human settlements since wolf reintroduction in 1995. The wolves headed home last summer, but you might still spot them with help from one of the guides on the Yellowstone Association's fall discovery tours.
Peter and Maria Hoey
Although it lacks the rustic eye-candy factor of the famed Old Faithful Inn, Mammoth Hot Springs Hotel wins in an eco-smackdown. Its boiler system runs on cooking oil from park restaurants, saving 10,000 gallons of heating oil annually. Its gift shop, For Future Generations, has shelves made of reclaimed wood, which hold such ecofriendly products as note cards made of bison dung. And every piece of bric-a-brac has a "sustainability scorecard" attached.
The glut of cars and RVs in the summer season. Mammoth sits at an intersection of primary roads, and traffic around the hot springs' travertine terraces can be bumper-to-bumper. Yellowstone urgently needs to consider a shuttle system like the one Glacier National Park instituted in 2007.
Grab a fly rod and wade into one of the park's bazillion trout streams as a data collector for Yellowstone's fisheries management program. Info from your Volunteer Angler Report Card, issued with each fishing permit, helps officials monitor climate-change effects and combat invasive species. Volunteering never felt so lazy. —Brian Kevin