Celebrating 50 years of personal and professional partnership in the lives of lyricists Alan and Marilyn Bergman, Michael Feinstein’s new show at the Regency is a musical bonanza indeed. Each night features a special guest star. I was lucky enough to see the divine Mary Cleere Haran, who crooned “So Many Stars” with a sublime Brazilian bossa nova beat that could sink your heart. You never know whom you’ll hear. One night it’s Christine Ebersole. The next night it’s Marvin Hamlisch. And every night it’s Alan Bergman, who joins Michael to interpret some of his own lyrics with warm, whispery precision. I would be less than honest if I did not admit I’ve grown weary of “The Windmills of Your Mind” and “The Way We Were.” It’s not that they’re any less excellent than the rest of the Bergmans’ catalog; it’s just that I’ve heard them so many times they’ve become ossified. Still, people get married to “What Are You Doing the Rest of Your Life?” and divorced to “Where Do You Start?”, and you will never hear them sung better than in this show. In a freaked-out world of flash and trash, the Bergmans are unique. They write lyrics that are intelligent, penetrating and memorable, to music by such brilliant collaborators as Michel Legrand, Cy Coleman, Johnny Mandel, David Shire, Marvin Hamlisch, David Grusin and others—winning three Oscars and countless Tonys, Grammys and Emmys doing it. Plus, they’re so eclectic and prolific there’s always something new to discover. “We always feel like the words are on the tips of those notes, and we have to find them,” says Alan, who sings his own material softly, introspectively and full of irony, distilling from a limited vocal range a maximum of emotion. One highlight for me in this show is the way Alan quietly swings “That Face,” the valentine he wrote to Marilyn 50 years ago as a kind of marriage proposal. Another is Michael’s amusing lyrics to “The Best of Friends” (“When you itch, I scratch/ When you sleep, I snore/ That’s what best friends are for”). The five-man orchestra headed by Rosemary Clooney’s longtime pianist John Oddo honors the artistry of the Bergman lyrics with special affection. From Brazil to Broadway, from jazz to Yentl, the Bergmans have captured and polished an entire spectrum of music that has not only survived the fads and trends, but promises to be around for decades. Everything at Feinstein’s right now is a class act all the way.