Yesterday it was buses, not limousines: The participants in the inaugural social drama had to get where they were going fast, and together. The family of George and Barbara Bush, 130 strong, required four buses. Some buses served lunch -- with one fleet providing chocolate-dipped, liquer-marinated strawberries as dessert. At the John Sherman Coopers in Georgetown, over 100 guests on their way home from the day's festivities had choice seats on the balcony for the fireworks display that set off the night's celebrations. For the GOP, yesterday was prelude to an evening of balls. But for the Democrats -- including former vice president Mondale, who was home by midafternoon -- the postlude had already begun.

Roy Cohn was already in white tie and tails as he began introducing guests around at the 6 p.m. party that he and lawyer Tom Bolan were giving at the Madison Hotel yesterday.

Lots of New Yorkers -- Democratic, Republican, celebrity.

"There's Regine," said Cohn, a lawyer and -- as some put it last night -- New York power broker. "She's one of my clients. A strong Republican. You can't own a string of places, charge $100 to get in, and not be a Republican."

Regine, owner of Regine's in New York, on the inauguration: "I loved it when Reagan said 'entrepreneur.' Very, very French."

"Mr. Senator," said Cohn shaking New York Republican Sen. Alfonse D'Amato's hand.

"How are you, buddy?" said D'Amato.

"I want you to meet Frank Lorenzo of Texas International and New York Air which I flew here on . . ." said Cohn, slipping an arm around Lorenzo's shoulder and introducing him to D'Amato.

Around the sumptuous spread of hors d'oeuvres moved a variety of New York politicians and journalists in various stages of Inauguration Day dress.

"I'm floating from party to party with cheese puff in hand," said columnist William Safire. He was in business dress.

So was Roy Goodman, New York state senator from Manhattan. "This is my convertible attire," he said. "I have my bow tie in pocket."

Jery Zipkin was in business suit drinking white wine. "I've got two parties after the ball -- then head for the nearest hospital -- stretcher time," he said.

Mario Biaggi and Geraldine Ferraro, both Democratic congressmembers from New York, showed up. "An illustrious Democrat, and one of my favorites," said Cohn putting an arm around Ferraro.

Other guests: David Machoney from Norton Simon, direct-mail expert Richard Viguerie ("I was a great fan of Cohn in college -- he really helped solidify my concerns about communists") and Andy Warhol, taking pictures as usual.

"I've gotten a number of clients since the election," said Cohn. "But I want to make sure that they didn't think I was suddenly attractive. I want to make sure they satisfy my ego and think I'm a great lawyer."