The "London for less" discount card is good for a 25 percent discount on hotel rooms, up to 50 percent off tours and car rentals, up to 50 percent off major attractions, and up to 75 percent off plays, musicals, operas and concerts. The card, valid for two people for four days, costs $19.95. Additional cards are $8 a piece. Extensions for Edinburgh, Bath and York are $4.95 each. For more information, call 1-800-244-2361.
* HENDERSONVILLE, N.C., is in the heart of the Blue Ridge Mountains. Sites include the home of author Carl Sandburg in the town of Flat Rock; the Flat Rock Playhouse (one of the finest summer stock theaters in the country), historic Main Street in Hen-der-son-ville (listed on the National Register of Historic Places) and the Blue Ridge Parkway. The area's Mountain Seasons Vacation Planner lists special events and accommodations. For a free copy, call 1-800-828-4244.
* GUIDE TO NAVAJO AND HOPI NATIONS. "Native Roads: The Complete Motoring Guide to the Navajo and Hopi Nations," $19.95 paperback, describes self-guided road tours of northern Arizona including well-known Monument Valley, Canyon de Chelly and Lake Powell and not-so-well-known spots such as Coal Mine and Tsegi canyons. Author Fran Kosik traveled these roads as an Indian Health Service nurse. The book features 15 scenic highways and describes each of the Navajo regional rug designs at their place of origin. For information, call 1-800-809-5457.
* TEACHERS SWAP HOMES. The 1996 Teacher Swap Home Exchange Directory lists homes in the United States, the U.S. Virgin Islands, Canada and other foreign locations like France, England, Germany and Spain that are available for "swapping" with teachers. The homes listed are available for a simultaneous home exchange, bed & breakfast courtesies, or accommodations for a fee. The company merely lists the vacation homes and the times they are available. It does not negotiate between the parties and is not liable for any problems you might encounter from the transaction. The annual fee is $42 (first year) and $32 each year after that. For information and to request an enrollment form, send your name and address to Teacher Swap, P.O. Box 454, Oakdale, NY 11769-0454. March 25 is the deadline for placing a listing in the directory's April supplement.
* THE COLORADO DIRECTORY lists more than 200 commercial campgrounds, cabins and lodges throughout the state. For a free copy, send your name and address to the Colorady Agency for Campgrounds, Cabins & Lodges, Inc., 5101 Pennsylvania Ave., Boulder, CO 80303-2799, or call 1-303-499-9343 between 8 and 5, Monday through Firday. The association represents a majority of the commercial campgrounds and about two-thirds of the cabin resorts and traditional-style lodges in the state. They are considered affordable mountain accommodations with family owner/hosts.
* LUXURY LINE CRYSTAL CRUISES' 1997 Cruise Guide is hot off the presses. The 32-page brochure has details on the company's 1997 itineraries, which will include the South Pacific, South America and a World Cruise. It also lists land programs. To order a guide, call 1-213-340-4121, or send your name and address to Crystal Cruises, 2121 Avenue of the Stars, Los Angeles, CA 90067.
* DONT'T LET A TOOTHACHE RUIN YOUR VACATION. 1-800-DENTIST is a no-charge-to-the-patient dental referral service that operates throughout most of the continental United States. Dentists listed in the service's database have been carefully screened. All you need to do is call the toll-free number.