"We felt there was definitely a need for a daytime venue for, I don't want to use the term 'dayclub,' but that's how people are describing it," says Kallao, who was involved in the planning and implementation of the new adults-only pool. "This is an alternative for the daily pool person who comes out in the summer."

Tao Beach opened for the first time in May and so far, has been well-received, says Jason Strauss, managing partner of Tao.

"For us, it's just part of an overall experience," he explains.

Guests can lounge in cabanas playing Xbox video games on plasma-screen televisions or receive a massage. The beach is simply an extension of the nightclub, Strauss says, so the atmosphere is lively.

Guest surveys have consistently found that the pool ranks at the top with tourists as far as hotel amenities go, says Michael Gilmartin, spokesman for the Stratosphere.

And that is one reason why management decided to put so much effort into Bare, Kallao says.

"We in the business certainly appreciate that the pool is the number one amenity. The Mirage pool is open to everyone, but as the demographic tends to get younger, we wanted a place that was for adults," Kallao says, adding that about 30 percent of women choose to go topless by the pool. "You'd be very surprised how many people go out there and take their tops off. Some hotel guests want that experience."

Amanda White, visiting from Tampa, Fla., says she would love to visit a topless pool run by a nightclub because it's combining the best of both worlds: daytime and nighttime fun.

She says this while sunbathing topless at Beach Club 25 at the Stratosphere, one of seven topless pools on the Strip. Wynn Las Vegas offers guests an adult pool with European sunbathing (that's code for topless); Mandalay Bay has Moorea Beach and Venus is at Caesars Palace. The Flamingo opened Go Pool in late May.

Bare, Tao Beach, Go Pool and Venus are open to the public, but most charge some kind of cover.

Resorts offer the option not only to provide an amenity to guests but also because it generates revenue, says Tara Suther, a tourist from Minnesota. If women go to a pool and sunbathe topless, as she was on a recent Friday at the Stratosphere, guys are going to follow.

"It draws a crowd. A lot of clubs charge to get in and they're going to have to pay at topless pools, but it's like a cheaper topless club," Suther says.

In her many years of topless sunbathing, Vicki, a tourist from California who declined to give her last name, says she has noticed that most men at topless pools are with a wife or girlfriend. The peeping element is less of a factor than the no children rule, she says. That's why she likes the option. She was enjoying the mostly quiet scene by the Stratosphere pool on a recent Friday.

Women go topless, she says, because they want to go home and say they've done something risque in Las Vegas.

"They're curious," she says. "I don't know if it's more about doing something naughty when they're here or the idea of what happens in Vegas stays in Vegas."