There are some things one never needs to see on a Broadway stage...like 82-year-old musical-theater grande dame Barbara Cook grabbing a costar's butt. Granted, the ensemble of Sondheim on Sondheim is excerpting A Funny Thing Happened on the Way to the Forum a show built on bawdy comic bits but Cook's goose is merely one of this schizophrenic show's many flabbergasting moments. Here's another: Tom Wopat romancing Leslie Kritzer, who's young enough to be his daughter. Oh wait, she was his daughter in the 2008 musical A Catered Affair.
The concept of the Roundabout Theatre Company's new revue, Sondheim on Sondheim, sounds like an overambitious senior thesis: Interviews with the composer-lyricist (some vintage, some newly recorded) play on a wall of LCD screens on stage, while actors perform his greatest hits, plus a few oddities and obscurities. But it's actually quite clever. Sondheim doesn't open up to journalists on a regular basis, so watching him work at the computer, his black poodles curled at his feet, or peeking at old photos (baby Sondheim, preppy Sondheim, Sondheim with a Dorothy Hamill 'do) feels a little like you're having an intimate chat with the master himself.
Sondheim on Sondheim is at its best when the composer gets to play tour guide through his oeuvre. It's a kick hearing ''Forget War'' the original opener to Forum alongside the now-famous ''Comedy Tonight.'' Or to see the three endings to Company: ''Multitudes of Amys,'' ''Happily Ever After'' which director Hal Prince called a ''downer'' (perhaps because of the line ''happily ever after...in hell'') and the ultimately produced ''Being Alive,'' which Norm Lewis absolutely kills. (Memo to Arlington, Va.'s Sondheim-happy Signature Theatre: Aren't you due for a Company revival? Sign him up.) And when else are you going to hear ''Smile, Girls'' which was cut from Gypsy after just one performance in Philadelphia? It's not a great song, but it gives gorgeous Ugly Betty star Vanessa Williams a chance to play Mama Rose (well, Wilhelmina Slater playing Mama Rose), and it gives Sondheim an excuse to tell his favorite foulmouthed Ethel Merman story.
But hamstrung by his too-eclectic cast and his obvious need to dole out work equally not to mention insert a big hit here and there conceiver/helmer/longtime Sondheim collaborator James Lapine cobbles together mish-mash medleys and moves songs too far out of context. We think Wopat and Cook are supposed to be a couple in ''You Could Drive a Person Crazy.'' (We think. In Company, it's sung by three girls driven bananas by the same boy, but there's no romantic tension between Wopat and Cook only a faint hint of annoyance.) After Williams pulls a runaway-bride act in the cut-from-Company ''The Wedding Is Off,'' the young-and-sassy Kritzer tells her to suck it up with Merrily We Roll Along's brilliant ode to pessimism, ''Now You Know.'' But shouldn't the older woman i.e., Williams be doling out the song's jaded sarcastic pearls of wisdom? (''It's called flowers wilt, it's called apples rot, it's called thieves get rich and saints get shot, it's called God don't answer prayers a lot. Okay, now you know.'') And we're still trying to figure out why, after Sondheim pays tribute to his teachers, we get ''Send in the Clowns'' other than, well, the audience wanted to hear ''Send in the Clowns.'' (It's beautifully rendered by Cook, of course, and giving it to anyone else would have been an insult to Catherine Zeta-Jones, who's doing her own lovely rendition six blocks south in A Little Night Music.)
Alas, not all of the actors can handle any Sondheim song that's thrown their way. Williams actually does; she's in her element, and she gets better and better as the show goes on her ''Losing My Mind,'' paired with Cook's ''Not a Day Goes By,'' is a complete heartbreaker. Lewis is spectacular. But Wopat, who's become a very fine stage actor since his Dukes of Hazzard days, doesn't have the range vocal or otherwise for Sweeney Todd's ''Epiphany,'' a fact that's only underscored by Sondheim's video interruptions discussing the song's shifting moods. In Sunday in the Park With George's ''Finishing the Hat,'' Wopat is marginally better, but as he sings he paces back and forth and clutches an artist's sketch pad almost for dear life. However, Cook is brilliant when she simply sings a Sondheim standard as she does in her concerts; that's what she's famous for. No one can touch her interpretation of ''In Buddy's Eyes.'' But she doesn't fit into a revue.
Sondheim, however, fits in perfectly and proves to be quite the ham. He even wrote a new song, ''God,'' poking fun at his own veneration. And if that box he showed us really did contain his fingernail clippings, forget sending them to the Smithsonian. Auctioning them off could pay for that long-awaited Merrily We Roll Along revival. B-
(Tickets: roundabouttheatre.org or 212-719-1300)