"The Life and Adventures of Nicholas Nickleby," the trend-breaking 8 1/2-hour British import that commanded an unprecedented $100 a seat during its limited Broadway run, carried off the Tony Award for best play last night, as most crystal balls had predicted.

But "Nine," a lavish stage adaptation of Fellini's surrealistic movie "8 1/2," pulled a minor upset by winning best musical over Michael Bennett's "Dreamgirls" and was chosen in four other categories, including outstanding direction of a musical (Tommy Tune) and outstanding score (Maury Yeston).

"Dreamgirls" had the consolation of winning six Tonys of its own, the most deserved going to Ben Harney and robust Jennifer Holliday, as outstanding actor and actress in a musical.

Roger Rees, who played the marathon title role in "Nicholas Nickleby," was named outstanding actor in a play. Zoe Caldwell scored as outstanding actress in a play for the title role in "Medea," which was produced at the Kennedy Center earlier this season and subsequently went to Broadway. Caldwell's performance was all the 620 Tony voters--journalists and theater professionals--apparently admired in the production, however. Dame Judith Anderson, nominated as outstanding featured actress in a play for her portrayal of Medea's aged nurse, lost to Amanda Plummer. Plummer got that Tony for her Agnes in "Agnes of God," a metaphysical mystery play by former Catholic University student John Pielmeier.

The 25-year-old Plummer, the only performer nominated in two categories, was also up for outstanding actress for her work in "A Taste of Honey," and her father, Christopher, was in the running for outstanding actor as Iago in "Othello." The family lost both times.

"Othello," which opened the Washington season last fall at the Warner Theatre, was chosen as the best revival of a play or musical.

The celebratory mood inside the Imperial Theatre, where the 36th annual ceremony was held, took no account of the fact that Broadway has suffered its first decline in attendance in eight years, dropping this season to 10.1 million from last year's all-time high of 11 million, and productions decreased from 60 to 48. Musicals, Broadway's usual drawing card, were in especially short supply. Despite the nomination of "Pump Boys and Dinettes" and "Joseph and the Amazing Technicolor Dreamcoat," two off-Broadway shows brought to Broadway to fill the obvious void, the competition boiled down to a race between "Dreamgirls" and the last-minute entry "Nine." So far neither show has attained the blockbuster proportions that make Broadway breathe easier.

Adding to the overall gloom, two historic Broadway theaters fell to the wrecker's ball earlier in the season. Milton Berle, not always one for topical humor, nonetheless got off the best one-liner in the two-hour ceremony. After one of his jokes fell flat, a musician in the orchestra pounded out a boom on the bass drum. "Don't tell me they're tearing this one down, too," a startled Berle quipped.

Some members of the New York theater community had sought earlier to remove "Nicholas Nickleby" from the competition, on grounds that it was a special event from a heavily subsidized English theater troupe--the Royal Shakespeare Company. The nominating committee put it up anyway, and true to expectations, it beat out " 'Master Harold' . . . and the boys," "Crimes of the Heart" and "The Dresser" for best play, and also won for outstanding direction of a play (Trevor Nunn and John Caird) and scenery.

Playwright David Edgar, who adapted the work from Charles Dickens' 1,000-page novel in collaboration with the RSC actors, accepted the Tony "on behalf of over 100 living people and one dead one," and also duly thanked the British taxpayers, "without whom it would have been $250 a seat." The remark pointed up a sad reality: Producing a play on Broadway these days is economic suicide. Subsidies are the theater's only salvation.

South African actor Zakes Mokae, who appeared at Arena Stage last September in Athol Fugard's "A Lesson From Aloes," won outstanding featured actor in a play for his performance in Fugard's latest drama about the agonies of apartheid, " 'Master Harold.' " Actress Liliane Montevecchi edged out her co-performer, Washingtonian Karen Akers, as outstanding featured actress in a musical (both are in "Nine"). "Nine's" sumptuous costumes by William Ivey Long took the award in that category.

"Dreamgirls" was also given Tonys for best book (although the award, which went to Tom Eyen, inexplicably was not announced on the show), outstanding featured actor in a musical (Cleavant Derricks), and outstanding lighting (Tharon Musser). However, the show is largely considered to be the brainchild of choreographer/director Michael Bennett, who's been trying for several seasons to duplicate his previous smash, "A Chorus Line." Although "Dreamgirls" is short on dancing, Bennett and his co-choreographer Michael Peters won for outstanding choreography. It was Bennett's seventh Tony.

"Dreamgirls," a multimillion-dollar musical, traces the rise to stardom of a singing group not unlike the Supremes. Toward the end of the two-hour telecast, Jennifer Holliday performed her first-act finale, "And I Tell You I'm Not Going," with the raw intensity she brings nightly to the role of an overweight soul singer, bounced from the group before it hits the big time. Minutes later, Holliday came back to the stage to pick up her Tony for outstanding actress in a musical.

She thanked God, her mother, the cast and Michael Bennett, although she had stormed out of "Dreamgirls" during its Boston tryout after a highly publicized run-in with Bennett. "You wannna fight again?" she joked from the stage, clutching the statuette to her ample bosom.

In between awards, the telecast focused on hit musicals that have played the Imperial Theater, a list that includes some of the plums of American musical comedy. But Cher, in a skimpy black-lace teddy, badly lip-synching the words to that Cole Porter classic, "My Heart Belongs to Daddy," couldn't recapture Broadway's past glories. For all of the hoopla around the Tonys, the Great White Way was looking dingy.