Broadway stages have never looked so bare. Big stars like Billy Crystal, Whoopi Goldberg, Mario Cantone, and Dame Edna are currently starring in solo vehicles, as is everyone’s favorite vagina monologuist, Eve Ensler, whose new body-part show moves the discussion north to her belly roll. The good news is that the Tonys might be funny this year. The bad? Most of the work seems like the theatrical equivalent of the theme restaurants colonizing the new Times Square.

Why are these luminaries going it alone? The reasons range from ego (who needs a second banana?) to economics (a cast of one is a helluva lot cheaper than a teeming musical). Clearly there’s also a craving for something more direct and vital than typical Broadway fare. The $100-a-pop nostalgia rides—from Mamma Mia! to the screen-to-stage musical fiascos—have become exasperating, to say the least.

Yet there’s something undeniably retro about the current solo phenomenon. For one thing, the acts tend to fall into the category of traditional stand-up. Cantone and Dame Edna would have given Don Rickles and Totie Fields a run for their money, while Goldberg and Crystal are essentially offering formulaic Emmy-winning television comedy specials.

Performance art this is not. Soloists like Eric Bogosian, Karen Finley, Tim Miller, and Holly Hughes—artists who mined their most private selves for public revelation—are a vastly different breed from Oscar hosts. Try to imagine Whoopi or Billy covering themselves in chocolate sauce to convey the shame of childhood sexual abuse. Suffice it to say, radical vulnerability and the Academy Awards do not mix.

What’s curious is how even the less mainstream personalities are purveying carefully packaged personas right now. Cantone offers a glitzier version of his Caroline’s routine, the exasperated-Italian American-queen shtick that won him a recurring part on Sex and the City. Dame Edna has timed her stage “comeback” perfectly with the release of the boxed DVD set of The Dame Edna Experience. And while Ensler may be courageously exposing a middle-aged midriff, she’s pursuing tactics similar to those used in her Vagina Monologues.

Stars with the most Hollywood wattage can’t help but outshine the competition—at least in the publicity arena. The Post has dubbed Crystal “King of Broadway,” though king of schmaltz would be more apt. 700 Sundays is like a carefully staged infomercial, funnier than his Barbara Walters interview, though somehow less emotionally credible.

Standing outside a replica of the Long Beach tract house he grew up in, Crystal shows home videos, which, thanks to his illustrious jazz heritage, aren’t totally devoid of interest. His father ran the legendary Commodore Music Shop on East 42nd Street. His uncle, Milton Gabler, was a recording-industry mogul who worked with Billie Holiday, Louis Armstrong, and Ella Fitzgerald and produced the song “Rock Around the Clock.” When Crystal was a boy, Holiday took him to see the movie Shane, a detail that gets gobbled into the legend of how a guy little more than five foot seven—a baseball fanatic whose teen heart was broken when his father passed away—became the favorite emcee of “Hollywood’s biggest night.”

Despite the pleasure of Crystal’s genial company, the stories bear a postcard’s relationship to truth. His lucrative genius is for pushing all the right baby-boomer buttons—the sophomoric jokes (about his obstreperous teenage penis and flatulent grandfather), the sentimentality (his journey from Nassau Community College nobody to household name, his mother’s eventual stroke). For two and a half hours, the audience indulges him, and by extension their own neighborly sense of themselves. Crystal is, after all, one of us. Ask his buddy Joe Torre if you don’t believe me.

Goldberg doesn’t bother to retread her storied past (from the housing projects to Beverly Hills) in Whoopi, a star vehicle that recycles characters from her Broadway premiere 20 years ago, the show that put her on the map. An icon every bit as big as Crystal, she sells her sensibility rather than her story. Goldberg doesn’t so much act as deploy her personality. A raised eyebrow sends her audiences into convulsions, and when she pauses, they stop breathing.

The first third of Whoopi is strong stuff. As Fontaine, a male junkie who’s an unusually astute political observer, Goldberg updates the character’s monologues and bags herself some Bush. “I went to bed after 9-11 hearing we wuz going to war in Afghanistan,” says Fontaine, in a permanent druggy haze. “I woke up the next day and we wuz in Iraq!” Commenting on the capture of Saddam, he asks, “How hard can it be to find Osama, a seven-foot guy in the desert dragging a dialysis machine?”

When Whoopi’s unplugged (talking to the audience, riffing on one of Fontaine’s news flashes), you understand how she got as far as she did. A sense of daring charges the air like an oncoming storm. But when she’s pulling old characters out of her trunk (a pregnant Valley girl, a physically disabled woman being unexpectedly romanced), you see the limits of her talent. Goldberg makes cartoons of cartoons. She doesn’t have Ruth Draper’s fabled ability to birth nuanced multitudes; nor does she have Lily Tomlin’s knack for breathing unexpected life into loony types. Goldberg’s at her best when she’s peeking out of a role, a sly clown breaking through claustrophobic convention.

In Laugh Whore, a solo grab bag of dish and dirt, Cantone starts off uproariously—he’s a sniper let loose on Entertainment Tonight. Crawling up and down his stool (on a set decked out with white bulbs like a ’70s variety show), he relates celebrity vignettes National Enquirer-style. As an actor in other people’s plays, Cantone can’t shake his own seething sissy persona, yet he’s a first-rate mimic. Moving from a soused and jowly Shelley Winters on Inside the Actors Studio (“I fucked all my leading men . . . Kirk Douglas, James Francis, Tony Franciosa, Lauren Bacall”) to his own Mommie Dearest transformation in the backseat of a cab (“I told you to drive up Sixth Avenue across 44th Street. Why must you defy me?”), he wields a face of Silly Putty and a taut little Chelsea body that will wiggle into any position to skewer the rich and famous.

Hostility becomes him. No one in the history of show business has invested the word friggin’ with so much comic fury. Stabbing his index finger in the air, he punctuates anecdotes with paroxysms of common sense (“You guys, Cher has an Oscar!”). But all the anger in the world can’t sustain the helium heights of Laugh Whore‘s opening. Determined to give us a full evening, Cantone exhausts himself and his material. The increasingly potty-mouthed antics devolve into a Fire Island cabaret (exactly what he was accused of doing when he was the unlikely host of the kiddie show Steampipe Alley). Yes, he really does a Garland number (“My Name Is Gumm”), complete with tousled hair and syntax. By the time he reels off a string of amusing Vagina Monologues celebrity substitutes (Britney Spears: “My vagina has no talent”), he’s overstayed his welcome by a good 45 minutes. Still, the memory of that initial hilarity keeps us hoping for another fix.

There’s little chance that Cantone will be doing parodies of Ensler’s new show, The Good Body, a piece that seems like it was commissioned by Oprah Winfrey. Do people really want to pay Broadway prices to hear a successful theater person rant about her paunch? Genitals at least carry the frisson of the forbidden. Flabby stomachs, as anyone who has strolled on a beach can attest, have no such allure. Were it not for the breakout success of The Vagina Monologues, Ensler’s latest wouldn’t have had a prayer of getting produced. Unlike Cantone, she’s not adept at caricaturing others (she’s too nice to be truly cutting). Worse, her wit comes laced with self-help messages, the dividends of her travels from Helen Gurley Brown’s office to sharing a bowl of ice cream with a burka-wearing Afghan woman. “I eat the ice cream for women in Kabul and Kandahar,” she says. Well, everyone has to take a stand sometime.

The franchise known as Dame Edna sticks to one noble crusade—the attainment of maximum profits. No price is too great for her devoted fans to pay for the honor of being insulted by the purple-haired hausfrau from Oz. As she explains early on in Dame Edna: Back With a Vengeance, “This show is all about you. How you fit into the human scheme.” She has other ways of describing what she does (“cutting-edge caring,” “tough love”), but what’s telling is how her victims can’t get enough. Take, for instance, the middle-aged businesswoman from Queens, whom Edna cross-examined with a battery of real estate questions (“Do you have a view, dear? I want you to tell me exactly what you see outside your window”). That her mark publicly admitted to an outer-borough address was all Edna needed to go on one of her “empowering” rampages.

Somehow no one gets offended. Her targets are willing not only to give up their shoes for Edna’s psychic readings (otherwise known as “pedomancy”) but later to come up on stage and enact her life story. Why do these humiliated dupes look like they’re having the time of their lives? Because Edna’s creator and alter ego, Barry Humphries, is a consummate, not to say corrosive, wit.

While Crystal does everything to convince us that he’s still Billy from the block, and Goldberg that she’s still down with the people, Edna revels in her own flagrant fraudulence. She a genuine fake. Perhaps this explains why she’s better at staying in character than her solo rivals: She understands what her possums are paying for, and by God, she’s going to give it to them.