Holders of American Airlines' discount coupons, which are redeemable on American's Caribbean flights if the trip is completed by midnight Dec. 9 (excluding the Thanksgiving holiday period, Nov. 20-26), are contributing to the airline's currently "heavy" booking picture at Dulles Airport, American confirms. A recent check showed few seats remaining. There are now only three flights a week to Puerto Rico and one to the U.S. Virgin Islands.

Daily service from Dulles to St. Croix-St. Thomas and San Juan will begin on Dec. 13, in time for the Christmas period.

American reported recently, however, that is still had space "to all Caribbean destinations" from its New York gateway up to Nov. 20 and from Nov. 27 to Dec. 12. Routes from Washington to the West Coast are usually not as heavily traveled as the Caribbean, a spokesman added, but coupons are also being used out of Washington on long-haul domestic destinations. One those routes coupon holders must complete flights prior to Dec. 15.

United Airlines, which originated the half- fare coupons to speed recovery from a crippling strike, reported that they are bewing used more on "long-haul flights" from Dulles to Denver, Seattle, San Francisco and Los Angeles. Trips with United coupons must be completed prior to Dec. 15.

A United spokesman said many travelers are using their coupons to sample the first-class cabin. Busch 'Gardens "No. 1"

Busch Gardens' "The Old Country" in Williamsburg, which ended its 1979 seven-month season Oct. 28, has reported its second-best attendance figure in the park's five-year history. There were a total of 1,920,000 visitors, compared with 2,171,000 for the season last year.

"considering the gas situation this summer and unseasonably wet weather in Williamsburg, we were pleased with the attendance and with the fact that Busch Gardens maintained its position as the No. 1 tourist attraction in Virginia," said William H. Thurman, general manager of the Busch Gardens Division. The addition of the Loch Ness Monster roller coaster in 1978 was credited by Thurman with stimulating attendance that year.

Kings Dominion at Doswell, the state's other major outdoor amusement park, whose six-month season ended Nov. 4, reported an attendance of 1,736,000 at the end of September, compared with 1,756,000 for the same period in 1978. Final figures are not yet available.

"we have snapped back after the gas crisis," a spokesman said. On June 1 the park opened its newest attraction, "The Lost World."

According to the Virginia State Travel Service in Richmond, no official yearly standings list is published for major state attractions because, in the case of some histroic areas and natural attractions such as Skyline Drive, no firm attendance figures are available. Colonial Williamsburg, cited by state officials as probably "the most well-known, most asked about" Virginia attraction, estimated its attendance this year will be around 1 million. Spielman Wins Award

Andy J. Spielman, vice president and executive director of Waters Travel Service, 888 17th St. NW, has received the Joseph W. Rosenbluth Memorial Award, which is presented annually to the agent making the greatest contribution to the travel industry.

In a ceremony at the 49th annual World Travel Congress in Munich, Nancy J. Stewart, CTC, senior vice president of the American Society of Travel Agents, praised Spielman, an ASTA area director, as "a man of ceaseless energy and enormous drive who has served both ASTA and the travel industry well for more years than he cares to remember." "Israeli Breakfast" Reprieved

The famed "Israeli breakfast" is still alive and fattening, despite earlier published reports to the contrary, according to Israel tourism officials.

The Jerusalem Hotel Association, which had announced that it would eliminate the generally free buffet at all major hotels on Sept. 15, due to rising costs, has rescinded its plan. From a tourism standpoint, the idea apparently was not kosher.

The lavish, hearty-style breakfast, a product of the kibbutz movement, usually comes with the room but should never be confused with the token meal euphemistically called the continental breakfast. Booklet on Cruising

Thinking of getting your feet wet (figuratively speaking, of course) on your first sunny Caribbean cruise? Cruise Lines International Association's free 12-page booklet, "Is Cruising Really For Me?," is now in its third printing "with more than 2 million copies in distribution," according to CLIA.

The booklet covers, as the subtitle indicates, ". . . And All the Most-Asked Questions About Vacations at Sea" -- and gives positive answers, naturally. Copies are available from your travel agent, or send a self-addressed, stamped envelope to CLIA, 311 California St., San Francisco, Calif. 94104.