Washington is a city of hand-tailored suits and chauffeured limousines waiting outside mahogany-paneled offices; a city of competition, power, back- slapping and private jokes where deals are cut in marble hallways or over bloody steaks.

Washington is a man's town -- by day.

But when the sun sinks behind the monuments, business moves to lace-trimmed buffet tables. The cabinet member the congressman couldn't reach earlier can be cornered behind the Russian caviar. Yesterday's AWAC vote is rehashed over birthday cake at a party for Nancy Thurmond. Ursula Meese gets Frank Sinatra to attend the ambassador's ball, and $270,000 is raised.

Washington belongs to women -- by night.

"When you get right down to it, women control the guest lists," says hostess and writer Jayne Ikard. "I don't invite people to my home for business, but I know people have met here who should have known each other and deals have been made . . ."

"I don't know whether exact business is done, but people certainly become better acquainted though socializing," says Jean Smith, wife of Attorney General William French Smith. Like many of her California contemporaries, Jean Smith has become a familiar part of Washington's social landscape. "It's easier to see people in a business setting when you've already met them socially . . . I suppose women are responsible for this."

Fun is secondary to the Washington social whirl. Flags are waved; dollars are raised. Women have always artfully controlled exposure and influence in this arena, from businesswoman Anna Chennault's well-publicized Republican soirees a decade ago to Pamela Harriman's high-powered private evenings in Georgetown, where big-name Democrats plot policy and finances surrounded by priceless Manets and Van Goghs.

And while some women orchestrate twinkling dinners, others choose which parties their husbands should attend.

Most weeks, 45 or 50 social invitations--from silky teas to formal balls -- flood the desk of presidential counselor Edwin Meese, but he rarely sees them. It is Ursula Meese who plows through them, sometimes twice a week, deciding where the couple will go. She and her husband's secretary eventually computerized the Meeses' schedules.

"For several hours every week, Ed's secretary and I go through them and decide . . . I try not to look at them as obligations . . . ," she says.

Nancy Thurmond, wife of Sen. Strom Thurmond (R- S.C.), interweaves power, charm and influence. While her husband was chairing the Senate Judiciary hearings on the confirmation of Sandra Day O'Connor last fall, Nancy Thurmond was hosting intimate receptions for members of the committee, their wives and various cabinet members.

"The intent was not to influence," explains Nancy Thurmond. "But we thought it important for people to know her in a relaxed, social way. And she wanted to meet people: I have always said that being the wife of a prominent figure is a full- time career all in its own."

Selecting just who is coming to dinner these days is an art, a game of subtlety and timing, of knowing who is not speaking to whom or to whom one wants to speak.

Joan Braden, a public relations executive, is a master at the task. For 25 years, Braden has brought the nation's powerful into her living room. Her parties are rarely covered by the press -- a clear sign of serious politicking.

During the Carter years, she says she decided that the right people were not getting together and that Washington needed intellectual stimulation. So every two weeks the Bradens would host thematic, off-the-record dinners. It was a chance for Carter men, such as Stuart Eizenstat, to exchange policy thoughts with Republicans such as Sens. Paul Laxalt of Nevada and Howard Baker of Tennessee.

"We'd pick a current topic -- like the Mideast -- and it would be discussed . . . ," says Joan Braden. "I don't think the Carter people felt comfortable about the press, and this was a way to assure them it (the conversation) was not for publication."

More recently, Braden hosted a book party for Henry Kissinger during the height of the Falklands crisis. The two-hour party turned into a night of intrigue. Secretary of State Alexander Haig called from London to brief assistant secretary of state Lawrence Eagleburger. Senior statesman Averell Harriman expressed his view that the United States should be staunchly behind London. Argentine ambassador Esteban Takacs used the opportunity to defend his country's position. And Henry Kissinger held court as important people whispered in his ear about recent developments.

The amount of prestige, money and power a woman (or her husband) has in Washington helps determine influence. But it is not always necessary to be rich, powerful or famous to get a good crowd. Just eager. But not too eager.

Consider Mary Jo Campbell, not exactly a household name on the glamor circuit. The former New York public relations executive is married to Doug Campbell, a public relations consultant at the Department of Energy.

Through networking, she has been able to bring mainstream Washington to their English Tudor house. "Interestingly enough," she says, "it hasn't helped Doug."

At least two of her parties received prominent press coverage:

* At a surprise birthday party for Nancy Thurmond, the guest list included Attorney General Smith, Agriculture Secretary John Block, Senate powers Ted Stevens (R-Alaska) and John Tower (R-Texas), Clare Booth Luce and Helga Orfila, wife of the secretary general of the Organization of Amrican States.

* A cocktail party for Wolf Trap founder and donor Catherine Shouse following the theater's devastating fire was viewed as a kick-off for a massive fund-raising drive. Luminaries overflowed the doors: Associate Justice O'Connor; Midge Baldrige, wife of the secretary of commerce, and Lady Henderson, wife of the former British ambassador.

Campbell also hosts monthly black-tie dinners for ambassadors, congressmen and White House aides. "I've seen deals made right in my living room . . . ," she said. "You get involved in this sort of thing through a network. For me, I got tired of the sandbox set, so I started volunteering to work on committees.

"Through that you meet powerful and interesting people and then it just happens . . . You end up working with the top people who are involved because of their positions . . . and then you're invited to parties you wouldn't automatically get invited to. Before you know it, you're part of the social scene . . . Before you know it they're coming to your parties and you're influencing the power base." graphics /photo: BY HARRY NALTCHAYAN A power party introduction--Nancy Thurmond, center, introduces Supreme Court Justice Sandra Day O'Connor, right, to Jeane Kirkpatrick, ambassador to the United Nations, at a tea Thurmond sponsored last year