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, liqueur-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.

"To freedom," chorused Washington's diplomatic corps as Chief of Protocol Abelardo Valdez led them in a toast yesterday after announcing that the 52 American hostages finally had been released by the Iranians. The impromptu salute came at a Blair House luncheon Valdez gave for the diplomats, his last official act before relinquishing office at midnight.

Eight buses shuttled some 400 diplimats from the swearing-in to the Blair House luncheon where the hostage story upstaged President Reagan's inaugural speech as the day's major topic.

"Excellent, complete, strong and perfect," said Saudi Arabian Ambassdor Faisal Alhegelan of Reagan's speech.

Soviet Ambassador Anatoliy Dobrynin looked considerably more amiable than he had earlier when CBS television flashed him on screen, wearing a stony-faced expression, listening to Reagan describe "enemies of freedon."

"He spoke about a new effort," said Dobrynin. "I hope the new effort applies to new relations. Our government is prepared."