Many trip organizers specialize in only one type of activity; however, a few companies guide different kinds of active trips. (In some cases, these larger companies also act essentially as a clearinghouse or agent for smaller trip outfitters.) Be sure to sign on with a reliable outfitter; getting stuck with a shoddy operator can be disappointing, uncomfortable, and even dangerous. Some sports—white-water rafting and mountaineering, for example—have organizations that license or certify guides, and you should be sure that the guide you're with is properly accredited.
Those in their golden years can participate in special tours. Some of them are quite adventurous, such as Elderhostel's grandparent-grandchild river rafting cruise down Grand Canyon's Colorado River.
If you want to concentrate solely on one park, contact the park directly to learn about organized tours they may have.
Grand Canyon Tour Company. This operator provides tours of the park—by bus, helicopter, or plane—from nearby Las Vegas. They also offer guided rafting, hiking, and overnight camping trips in the park. 3014 S. Rancho Dr., Bldg. A, Las Vegas, NV, 89102. 702/655–6060 or 800/222–6966. www.grandcanyontourcompany.com.
The Yellowstone Association Institute. The field institute of this nonprofit offers educational seminars and guided one-day and multiday tours and trips for adults and families in Yellowstone, ranging from backcountry expeditions to "Lodging and Learning" experiences. 406/848–2400. www.yellowstoneassociation.org.
Tours with Accessibility
Access Tours. This group leads eight-to-12-day trips into U.S. and Canadian national parks (and other Western destinations) for people who use wheelchairs or have other mobility impairments; trips can be customized for small groups. 800/929–4811 or 208/787-2338. www.accesstours.org.