On the East Coast, we live amid much greenery, so America's western deserts may seem bleak and barren. But there can be great beauty in the varied shapes and colors of giant rocks, the sturdy pose of tall cactus and the sweep of the proverbial wide-open spaces.

To enjoy the desert, go in the winter when temperatures are mild. If you want comfort along with the scenery, consider one of these fine resorts of the Southwest:

*Tanque Verde Guest Ranch, Tucson: The emphasis is on horseback riding at this luxury dude ranch on the edge of the Saguaro National Monument, home of the giant saguaro cactus. Choose a breakfast ride, picnic ride or all-day ride. Afterward, heated pools, indoors and out, soothe saddle aches.

*Arizona Inn, Tucson: It's an adobe hacienda, painted a gorgeous coral and set on 14 garden acres near the University of Arizona. The 86 cottage rooms, none decorated alike, are filled with antiques.The Arizona Biltmore, Phoenix: A large, but gracious old resort, it snuggles up to the base of Squaw Peak on 39 lushly landscaped acres. Full facilities include two 18-hole golf courses, 17 tennis courts and three swimming pools.

*The Wigwam, Litchfield Park, Ariz.: Golf is the lure of this fine old 75-acre resort located on the western outskirts of Phoenix. Opened 56 years ago, it offers guests three 18-hole golf courses, as well as eight tennis courts, two heated swimming pools and a stable. Spanish adobe is the style for the resort's 225 rooms, in one-story clusters of four, offering views of landscaped gardens, the mountains and, of course, the desert.

*The Boulders, Carefree, Ariz.: Guests stay in adobe casitas (little houses), each with fireplace and patio, at this new Rockresort about 15 miles northeast of Phoenix. The desert views are grand. Rancho de los Caballeros, Wickenburg, Ariz.: Desert and mountains surround you on this 20,000-acre guest ranch about 60 miles north of Phoenix. Horseback riding, of course, but there are also an 18-hole golf course, tennis courts, a heated pool, skeet and trap shooting and such Old West pastimes as square-dancing, cookouts and guest rodeos.

*Marriott's Rancho las Palmas, Rancho Mirage, Calif.: Located just outside the famed movieland resort of Palm Springs, where golf and tennis are the big attractions, the 450-room palm-shaded resort offers 27 holes of golf, 25 tennis courts, three swimming pools and lots of desert country to explore.

*La Quinta Hotel Golf & Tennis Resort, La Quinta, Calif.: Also located near Palm Springs, La Quinta, one of the earliest of the area's resorts, is nestled in seclusion in the foothills of the Santa Rosa Mountains. It's an 800-acre garden preserve of manicured lawns, reached by a long drive past rows of Italian cypress trees. Golf, tennis, swimming are part of the amenities, but so are the Spanish-style bungalow rooms, many with fireplaces for cool evenings. It has long been a favorite of Hollywood celebrities.

*Alexis Park Resort Hotel, Las Vegas: Unusual for Las Vegas, the new all-suite Alexis Park offers no gambling. The famed casino "Strip" isn't far away if that's what you want, though you might be tempted, instead, to relax by the pool beneath a desert sun.