Sheila Patton, the first lady's press secretary, and William Tate, a Virginia insurance agent, are getting married in exactly three days. And then they're taking a honeymoon to the Homestead resort in Virginia. Relaxation, tennis, golf. The life -- for exactly three days. Power has its price.

"We've got the Japanese state dinner Thursday night," said Patton, "so I figure I've got to be back by Wednesday."

"And she will be," her husband-to-be said, a touch wistfully. He's new to the glamor of it all, and as for the spotlight, "I can take it or leave it."

They were definitely taking it last night in Georgetown, where Patton's old boss, public-relations wizard Robert Gray, had a dinner dance for about 100, azaleas on the tables and everything, in their honor.

White House Deputy Chief of Staff Michael Deaver stood in a corner with ABC-TV journalists Barbara Walters and Sam Donaldson. The guest list was heavy with media types (from UPI's Helen Thomas to People magazine), Patton being a press secretary and all that. Walters and Donaldson came to the party together. She wore pearls and pink taffeta, he was in basic black.

"Did you see the speech last night?" Deaver wanted to know.

"No," said Walters, "I was at Henry Kissinger's dinner for Jeane Kirkpatrick, and they didn't play it."

"She called to ask me if she should go to the dinner or the speech," Deaver said later of the U.N. ambassador. "I told her to go to the dinner."

Shortly after, Donaldson was standing near the stairs minding his own business, when he was approached by Mildred Hilson, a New York grande dame and occasional hostess of political dinners.

"Why do I know you?" Hilson wondered quite audibly as she pumped Donaldson's hand.

"Well, madame," said Donaldson gallantly, not missing a beat, "I drive a cab in the daytime, and I think I've picked you up from time to time."

"Sam!" said Walters. "I told him to put on a jacket tonight and behave himself."

She turned back to Donaldson. "Don't worry," said Walters. "She probably watches CBS."

Secretary of Health and Human Services Richard Schweiker and his wife, Claire, were standing in the middle of a glass-walled office, quite alone, perhaps seeking respite from the crowd. "We were admiring the office furniture," said Schweiker, running his finger along a rolltop desk.

He was sanguine about the flap over the Reagan administration's recent nominee for HHS assistant secretary, Warren Richardson, who withdrew his name from consideration Friday after charges of anti-Semitism were raised.

"That's what the press is for."

Gray got to know Patton when they worked together at the public relations firm of Hill and Knowlton. Gray was also deputy director of the Reagan/Bush campaign and co-chairman of the inaugural extravaganza. But he's got a public relations firm of his own now, and chums in the White House, some of whom were there last night, including brand new White House speechwriter Landon Parvin, who once labored at Hill and Knowlton himself.

Word was soon passed that dinner was being served, and coupled slowly made their way, arm in arm, down to the veal and wild rice.

But perhaps the most striking couple in the room were the inadvertent twins, two women in identical purple designer gowns. "I don't believe it," said the first.

"Honey," said lawyer Henry Dudley, to the second woman, "did I ever tell you about the time 15 years ago when Marjorie Merriweather Post and Perle Mesta were wearing the same $1,800 gown? Marjorie took one look said, "Perle, you've never looked better."