Six excellent musicians perform in “Dear Lenny: Bernstein’s Life in Songs & Letters,” but the surest sign of the revue’s cozy charm may be three feet. Specifically, the toes on three feet, rhythmically tapping during “I Can Cook, Too.”

That song, from “On the Town,” is a rare lyricless moment in the nearly sold-out “Dear Lenny,” which is heavily weighted toward Leonard Bernstein’s forays into musical theater, with only snippets of his classical music. At first, “I Can Cook, Too” seems like an odd choice to perform without the words; Betty Comden and Adolph Green’s hilarious lyrics, after all, have made it a cabaret staple for more than seven decades. But then, each of the three instrumentalists — pianist Dan Chouinard, bassist Greg Hippen and woodwind player Bruce Thornton — is given a jazzy moment to shine, with singers Bradley Greenwald, Diana Grasselli and Prudence Johnson all tapping their toes as they sit in the background, and we realize that, yes, the lyrics are swell, but it’s also a corker of a tune.

That’s a smart bit of curation in a show that occasionally feels less like a tribute to the late maestro, who would have turned 100 this Saturday, than to the lyricists who worked with him (not that I’m complaining). “One Hundred Easy Ways to Lose a Man,” from “Wonderful Town,” is another dandy song, but it’s Comden and Green’s lyrics, not Bernstein’s tune, that make it memorable. Still, recasting the solo as a quartet for men and women forces us to think about the song in a new way and pays tribute to the enduring power of Bernstein, Comden and Green’s work. And, lyrics aside, Grasselli’s brava-worthy delivery of the tongue-twisting “Glitter and Be Gay” salutes the indelible wit of Bernstein’s music.

A lot of great songwriting is spotlighted in “Dear Lenny,” which juxtaposes Bernstein’s music with readings of letters to and from him. The letters fill in details of his life (being blacklisted, his growing fame), offer encomiums to him (from, among others, a mid-20s Stephen Sondheim and a 10-year-old Yo-Yo Ma) and, in one especially thoughtful selection, shed light on his tortured personal life. Johnson reads a long portion of a letter from Bernstein’s wife, Felicia, assuring him that his homosexuality doesn’t mean their marriage must end. It’s a stunning piece of writing and it segues into a poignant, if wonkily arranged, Greenwald/Johnson duet of the finale of “Candide”, “Make Our Garden Grow,” which suddenly seems to be entirely about the compromises of a difficult marriage (“We’ll do the best we know”).

It’s usually a mistake to confuse the creation of art with autobiography, but “Dear Lenny” consistently makes thoughtful connections between the composer/conductor’s private correspondence and his public output. The show builds to a bracing encore, when the performers encourage the audience of 100 or so to join in on a number from “West Side Story” that is not just a classic song but also a powerful reminder that, time and time again, Bernstein’s music has guaranteed that “tonight won’t be just any night.”