BOSTON — The laughs, each a little earthquake, rumbled all the way out into the opulent lobby of the Emerson Colonial Theatre. Which must have come as an enormous relief to the fledgling director, John Benjamin Hickey, whose job it is to make them happen.

“I’ve never been more terrified,” Hickey said after the curtain came down on a recent Wednesday matinee of “Plaza Suite,” the three-act Neil Simon comedy being unveiled here before an official opening April 13 on Broadway, with Sarah Jessica Parker and Matthew Broderick each playing three characters.

“The first time I walked into the wings in the side of the house, I was like, ‘Oh, my God, I don’t want to see that the people are here,’” said Hickey, 56, an actor with voluminous stage credits himself. “I left Sarah Jessica backstage, both of us taking three huge breaths, both of us terrified in our own wonderful, unique ways.”

The “Plaza Suite” company had trekked to this city of academia and baked beans to revive not only a signature ’60s Simon comedy, but also a theatrical tradition that has all but gone extinct: the “out-of-town” tryout of a Broadway play. Musicals — generally speaking, far more complicated theatrical machines — sometimes still start with trial runs in such cities as San Diego, Chicago and Washington, the nation’s capital, the site for premieres of everything from the original “West Side Story” to the recent “Dear Evan Hansen.”

Plays, though, long ago ceased to make pre-Times Square stops because the costs of producing commercially have risen so radically. The modern equivalents of straight-play tryouts tend to be offerings in the seasons of nonprofit theaters off-Broadway or around the country, or in shows birthed in London. Broadway producers then pull these plays up by their fiscally sheltered roots and “transfer” them for potential box-office success to the Great White Way.

Gone are the days of scenes like those in “All About Eve,” the greatest theater movie ever made, when George Sanders, as a terminally malicious drama critic, traveled to New Haven to see Anne Baxter’s conniving Eve Harrington in a commercial tryout of a new play. The circumstances surrounding “Plaza Suite” — in its first Broadway revival since the Mike Nichols-directed original in 1968 starring George C. Scott and Maureen Stapleton — have brought those days rushing back. All thanks to a pair of stars who wanted that bygone theatrical experience, and a producer willing to bankroll them.

“There’s a wonderful historical vibe to it,” Hickey said, as he chowed down on fish tacos and a Caesar salad at a downtown Boston watering hole between shows. “Because you always heard about the Lunts being on the road, about Jessica Tandy and Hume Cronyn taking a show on the road. [Attention, kids: These were famous acting couples; Broderick and Parker are married, too.] And I think Matthew and Sarah Jessica have that old-fashioned strain of theater DNA in their bones.”

It may be that the expectations for this event make a test away from New York’s prying eyes particularly attractive. The work of Simon, Broadway’s most commercially successful playwright, who died in 2018, has been in a drought of late. His plays continue to be produced across the country, but the last big Broadway revival — a double bill of “Brighton Beach Memoirs” and “Broadway Bound” — shuttered prematurely in 2009. Should it be a hit with audiences, “Plaza Suite,” consisting of three playlets, all set in a room of the landmark Plaza Hotel on Fifth Avenue, would amount to a comeback for Simon, and a rebound for the Broadway boulevard comedy.

It’s also a bona fide test for Broderick and Parker, who have appeared onstage together only once — a 1995 revival of “How to Succeed in Business Without Really Trying,” in which Broderick played J. Pierrepont Finch and Parker succeeded Megan Mullally as Rosemary Pilkington. Both of their reputations, however, were burnished on Broadway: Parker at age 13 as Little Orphan Annie in the original production of the musical “Annie,” and Broderick at 21, debuting as Eugene Jerome in the original “Brighton Beach Memoirs.”

“The idea of going out of town was always at the forefront of Sarah Jessica and Matthew’s minds,” said Kristin Caskey, a lead “Plaza Suite” producer and head of U.S. productions for Ambassador Theatre Group. The Britain-based company’s U.S. theaters include the Colonial and Broadway’s Hudson Theatre, where the show heads after it finishes its Boston stay Feb. 22. Simon’s plays regularly tried out at the venerable Colonial, which was bought more than a decade ago by Emerson College and later restored by ATG. As a child actress, Parker appeared there, too.

“She told this story about the grandeur of the venue, and how she even remembered the coat check,” Caskey said of Parker. “She told us how she’s always kept that coat check tag.”

A tryout can be the time a production goes in search of its peculiar rhythm and voice. For Hickey — a Tony-winning actor (“The Normal Heart”) and friend of the stars with one previous directorial credit (“Bad Dates” at Playwrights Horizons) — the assignment, and the time in Boston, have been a godsend.

In Boston, set designer John Lee Beatty tweaked the plush “Plaza Suite” look on the stage of the 1,700-seat Colonial. Lighting designer Brian MacDevitt refined his design, and the actors were making the jokes — and Jane Greenwood’s costumes — their own. And the director — fresh from appearing on Broadway in “The Inheritance” — was experimenting with how to make the evening really move. One of those experiments involves tinkering with the intermissions. Originally, the show had two in part because back in the ’60s, Hickey said, “everybody smoked.” Now, he is seeing whether he can save time with one full intermission after the first act and a mere pause between the second and third.

“It’s a brand new play, to us,” he said. “The comic rhythms and the architecture of the play are just so unbelievably sound that it’s you learning how to serve the play. What you’re tuned to is ‘When is the audience ahead of the play? When did they get ahead of us?’ And when we feel them getting ahead of us, that means we have to tighten this, we have to move that. That’s the fun part, too.”

Traditionally, the tryout process involves the out-of-town critics, who are invited to weigh in with reviews that might help in gauging reactions or making adjustments (and perhaps even providing useful quotes for marketing purposes). But for “Plaza Suite,” the producers decided to make the official opening night, when critics are invited, the night before the show closes at the Colonial. According to Caskey, this has given the play “a proper preview period,” commensurate with what has been done with other shows in the space, such as “Moulin Rouge,” the musical that tried out here in 2018 and went on to Broadway last year.

That also means reviews are all but useless for Boston theatergoers; the run, in any event, is sold out.

And still, that other mainstay of early exposure — the butterflies — persist. On the first day of previews, Hickey emailed film and stage director Sam Mendes, who is a friend, to report on how nervous he was, having guided everyone to this moment.

“He said, ‘Dude, it’s like having a blind baby and letting it walk to the edge of a cliff by itself,’ ” Hickey said. “ ‘And you just have to stand there and watch.’ ”

Plaza Suite, by Neil Simon. Directed by John Benjamin Hickey. Through Saturday at Emerson Colonial Theatre, 106 Boylston St., Boston. Starts March 13 at Hudson Theatre, 141 W. 44th St., New York. $79-$549. 855-801-5876. plazasuitebroadway.com.