District-based hotels have included a bit of comparison advertising in a new promotional campaign for Washington tourism.

"Why go to the Big Apple when you can go straight to the core," states the programs initial print advertisment, published in Sunday editions of the Philadelphia Inquirer.

The advertisment bears a coupon with the illustration of a pointing finger designed in the shape of the Washington Monument. It was prepared for the Hotel Association of Washington by the advertising firm of Weitzman, Dym and Associates.

Persons who send the coupons to the D.C. group will receive a copy of a new brochure about member hotels and suggested tourist highlights for visiting families, singles and scholars. The ad doesn't mention New York City but focuses on the ambassies, Smithsonian, big stars, street cafes and cultural attractions of D.C.

Leonard Hickman, executive vice president of the association, said the campaign is designed specifically to promote weekend visits to Washington - when most hotels have vacant rooms after busy weekdays. Many hotels are offering special rates for weekend packages.

Rence Subrin, public relations director for the ad agency, said the new "straight-to-the-core" ad will be published next in the Philadelphia Bulletin, Wall Street Journal and dailies in Pittsburgh.