Washington doesn't often host movie-world weddings. But on Valentine's Day, Karen Dotrice, who started her career as the little girl in the film "Mary Poppins" with Julie Andrews, will marry Alex Hyde-White, who has just completed a film, "Untitled Comedy," in New York starring Dustin Hoffman and Warren Beatty and directed by Elaine May. The wedding, bringing in friends and family from across the country, will be at Grace Lutheran Church on 16th Street and followed by a reception in the home of Washington lawyer, Steven Martindale. The ever-sociable Martindale, who has been seen with less frequency over the past year, is out and about again. Martindale is Hyde-White's godfather.

Putting the complicated families into a genealogy: Dotrice is the daughter of Roy Dotrice, currently starring on Broadway in "Hay Fever" and known here for his Ford's Theatre portrayals of Lincoln and Churchill. Hyde-White's father is venerable British actor Wilfrid Hyde-White, who played Pickering in the film "My Fair Lady" and appeared at the Kennedy Center in "Jockey Club Stakes." He also had a successful television run in the series "The Associates." Karen Dotrice's sister Michelle is married to Edward Woodward, the star of the hot new television series "The Equalizer." Now that that's straight . . .

Among the glittery guests expected for the black morning-suit wedding are an impressive list of movie-world types including Dudley Moore, Stefanie Powers, Richard Pryor, Grace Jones, Dolph Lundgren, Kim Novak and Priscilla Presley. End Notes

It's been a big week for The New Republic magazine. It won the Washington Journalism Review's Most Insightful and Thought-Provoking Magazine award and Women's Wear Daily's "W" has proclaimed that The New Republic is on its "in" list, along with Irish whisky, cowboys and old Frank Sinatra tunes . . .

Those White House dinner parties end just a bit too early for some people. Television actor David Hasselhoff and his father Joseph Hasselhoff went from Tuesday night's dinner for Ecuadoran President Leon Febres-Cordero to the disco Desiree to close off the evening . . .

He'll never be "Back in the Saddle Again," but one-time singing cowboy, now superwealthy businessman Gene Autry is flying into town today. He'll be here to receive the Touchdown Club's Hubert H. Humphrey Humanitarian Award at its 51st annual awards dinner Saturday in the Sheraton-Washington Hotel. Actress Goldie Hawn will also be at the dinner to receive the club's Local Person Makes Good award. "Wildcats," a new movie with Hawn as a football coach, will be previewed at the West End Circle Theater Friday. Hawn is scheduled to present "Wildcats" team jerseys at the dinner to Walter Payton and William (The Refrigerator) Perry of the Chicago Bears and New York Jets quarterback Ken O'Brien . . .

These wealthy Palm Beach divorces do have a way of getting messy. Jacqueline Kimberly, wife of Kleenex heir James Kimberly, testified in a Palm Beach County Circuit Court Monday that her husband pulled a gun on her, chased her with a knife and monitored her telephone calls. "I still love him," Kimberly said. "But I won't live with him anymore." She wants overturned a prenuptial agreement limiting a divorce settlement and is asking $42,000 a year in alimony. The rich do lead interesting lives . . .

A man by the name of J.D. Stewart has selected this year's Dull Lifestyle Award winners: chicken king Frank Perdue; cartoon character Ziggy; wrestler Hulk Hogan; television personality Andy Rooney; model Brooke Shields; New York Mayor Ed Koch; CBS sports commentator John Madden; and actress Joan Collins. Winners of Stewart's Dull Brain award for public figures are Sen. Jesse Helms and sportscaster Brent Musburger . . .

Flaky as he is, news organizations can't seem to decide how to spell Libyan leader Muammar Qaddafi's (Post spelling) name. His name appears on the cover of four major magazines this week: Time, Gaddafi; Newsweek, Kaddafi; U.S. News & World Report, Qadhafi; and The Economist, Quaddafi. Maybe that's why he's so hard to get along with . . .