"Where's the beef?" said the woman in front of me as we walked into last night's opening-night party for "Other Desert Cities." As she cited this line from a 1980s ad for Wendy's, she was scanning one of the vast ballrooms of the Marriott Marquis hotel. But the answer to her question had just come across the street at the Booth Theater, where a triumphant performance of Jon Robin Baitz's play had just come down. And, if I may deconstruct my metaphor a bit, this entertaining drama contains not only the meat-and-potatoes basics of craft but the pleasures of more delicate fare: the kind of food mentioned in the play's first scene, as the Wyeth family prepares to celebrate a Palm Springs holiday with dinner at the country club. 

Given the spectacular nature of the play's reviews that were breaking online as party guests arrived, one could say that for Baitz, too - as well as for director Joe Mantello, and cast members Stacy Keach, Stockard Channing, Judith Light, Thomas Sadoski, and Rachel Griffiths - it's Christmas. As well as the other day of the year that promises presents: a birthday. As the party crested at the stroke of midnight, I found myself nudging the playwright and telling him that he could now celebrate not only the success of his play but his 50th birthday as well. "I'm thrilled" was about the only comment I could get out of him at that point. 

Other guests were more voluble. John Benjamin Hickey, a Tony winner this year for his performance in Larry Kramer's "The Normal Heart" (opposite Mantello), said: "I couldn't be happier for our playwright. It's a testament to how good the play is that it can accommodate not only the actors returning from the Newhouse production" - "Other Desert Cities" had a successful run earlier this year at LCT's Mitzi Newhouse space - "but two new ones as well." 

He was referring to Light and to Griffiths; the latter worked with Baitz on the TV show he created, "Brothers and Sisters." Both Channing and Griffiths quite literally let down their hair for the party, and doing so - stepping away from the entertaining but confrontational characters they play onstage - seem to release a kind of additional beauty. Both looked smashing. 

Also striking was party guest Renee Zellweger, in a long red dress, as if her event invitation, in the spirit of the play's timeframe, had read: "Holiday attire." Before the performance, Zellweger had skirted the official line but graciously posed for a few snaps just before going in. At the party, she told me: "I'm so happy I got a chance to see this play. The actors are so inspiring. It's enough to want to make me get up onstage myself." 

If I were an actor, I would feel the same. 

Brendan Lemon is the American theater critic for the Financial Times and the editor of lemonwade.com.