By Joe Brown

Wed, Feb 20, 2008 (2 a.m.)

Courtesy Photo

The day has dawned, the panting can stop. The Next Big Thing on the Strip is now open for business at Caesars Palace: the Bette Midler boutique.

Merchandisers have plundered pop culture warehouses for relics and souvenirs spanning Midler’s millennium in showbiz. That’s a lot of tchotckes. The singer/actress/comedian/philanthropist has been in the business for more than 40 years. In a career arc that has seen her go from campy kitsch retro-diva to Disney comedian to Johnny Carson’s favorite guest to ballad-belting earth mother and comforter to us all, Midler has racked up four No. 1 hits, four Grammy Awards, four Emmys and one Tony.

Among the Midlerabilia on offer: A signed, Swarovski crystal-encrusted ukulele. A “Divinity for Dummies” T-shirt. “Baby Divine” diaper-covering onesies. Baccarat crystal vases with etched autographs. Of course the store is soundtracked with purchase-promoting greatest hits, with a canned, crooning loop of the “The Rose” and other chestnuts on repeat mode from ceiling speakers. In a few months she’ll have to share shelf space with Cher, but for now it’s all Bette.

And there’s the little matter of the show next door.

It’s ... sparkly. And still shaky.

And it opens tonight at the Colosseum at Caesars Palace: “The Showgirl Must Go On.”

Can Midler possibly compare — commercially and artistically — with the mass-appeal monolith that was Cirque du Celine?

Midler braved two dress rehearsals in the 4,100-seat Colosseum on Sunday and Monday night before an invited audience, presumably stocked with family and friendlies. And although this is not a review of the show ­— critics are expressly gagged until sitting through the “official” Feb. 29 media performance — I can say that Midler and her crew are going to need every minute of the next 10 days to make it work.

And maybe a miracle.

And maybe even Barry Manilow.

Very much a work in progress, “Showgirl” may even require that most Vegas of renovations — demolition and reconstruction.

Here’s what I dare whisper about what I saw and heard:

Think pink. And vaudeville. Vegas Classic.

The new stage doesn’t look as physically dangerous as Dion’s did. But it is vast. And Midler, 62, repeatedly joked about being exhausted (let’s hope she was kidding), collapsing and panting on the floor. “That’s what happens when you do your own singing,” she cracked.

She’s contracted to perform five shows a week for two years.

Midler described her show Monday night as “a modest entertainment with a mere $10 million budget ... And 44 (breasts)!”

Her math may be off: I counted 20 “Caesar Salad Girl” chorines and three Staggering Harlettes backup singers.

You get to see them a lot. And a lot of them.

Midler waited about 10 minutes into her 90-minute act before making her first dig at Dion.

The 14 white-jacketed musicians are mostly in plain sight — including Las Vegas’ own six-piece Fat City Horns. Midler knows her audience: “Thirty years ago, my audience was all on drugs. Now they’re all on medication.”

Other Monday night revelations: You can buy rhinestone-trimmed panties in the lobby. And Robin Leach doesn’t turn his cell phone off during shows.

Can’t think of any must-hear hit she missed.

Go ahead, guess which song she picked for her final number.