I own one pair of dress shoes and I seldom wear them.

When I dig into my closet to unearth my fancy, black leather, square-toed, quarter-inch heel footwear, it's for one of two reasons: either somebody died, or it's time to review one of Luke Cusack's new clubs.

Recently, I visited Sapphire Lounge. It's the second club that Cusack has opened in the past six months, and his third overall.

Sapphire, which Cusack calls an "ultra lounge," opened its doors on New Year's Eve and has been a hot downtown spot ever since.

The club's most popular feature is its rooftop bar, which is often filled to capacity by 11:30 p.m.

The club has three floors. Downstairs, a long bar is bathed in blue light from three overhead chandeliers. Beyond the bar there are two grand pianos, the remnants of a failed experiment with live music.

"That's a sad story," Cusack says. "We wanted to do dueling pianos. We auditioned and auditioned and auditioned and we couldn't find anyone reliable."

Cusack says he plans to sell the pianos.

The club's second level has its own bar and a modest dance floor, as well as a few booths.

But the roof is where the action is.

From the sky deck, which boasts a bar and several portable heaters, revelers look out over downtown, including the neighboring blue and gray tower that houses Pima County Legal Services. At night, Centro, a competing lounge, projects its name on the south facade of that building.

Servers constantly circle the rooftop patio in search of empty glasses to take back to the bar.

If you want to hang out on the sky deck, you'll want to show up early.

After midnight, people on the first floor wait in line to get to the second floor and to the sky deck.

Even if you make it to the roof, don't expect to find a place to sit - that costs extra.

Couches and booths in the club can be reserved for $175 to $300 a night (the most in-demand seats are the most expensive). You also get to use the club's VIP entrance, and get to park in a VIP spot in the garage down the street.

On a recent Saturday night, women in cocktail dresses and men in button-down shirts mingled on the crowded rooftop, most with a drink in hand.

A group of young women, all in 3-inch heels, danced in a pack around a friend who was celebrating her 30th birthday.

House music played loudly over the speakers, forcing this reporter to shout his questions.

Eric Contreras and Marty Monaghan, two 20-something engineers who were enjoying drinks near the rooftop bar, said they thought the lounge was the right size and had a good mix of people, but needed more diverse music.

"I think if they're going to have different levels they should have different types of music on each floor," Contreras said.

Two elementary school teachers in their mid-20s, Casey Polich and Sara Anderson, stood around a first-floor table and complained about the dress code, which requires people wear dress shoes and "look nice." Jeans are allowed, provided they're not ripped or overly worn.

"This place needs a better variety of people," said Polich, who also hangs out at bars such as Cactus Moon and Cow Pony.

"Everybody's very metro," Anderson added.

Cusack says Sapphire does most of its business on Wednesday and Saturday nights, but he's optimistic the lounge's after-work crowd will grow as the weather improves.

"We really look to Sapphire to have a happy hour crowd," Cusack says, "with the sky deck and everything."

Starting tonight, Sapphire will host a Latin music night it's calling "Club Neo," which will feature salsa dancing and free lessons.

Before it was Sapphire, the three-story building at 61 E. Congress Street was Heart Five, which took a less upscale approach to nightlife.

After Heart Five closed nearly three years ago, the space sat unoccupied.

That changed on New Year's Eve.

Sapphire isn't Cusack's biggest nightclub. Just his latest.

First came Pearl, which Cusack opened in May 2007 on the site of his old club, The Keys.

A 20,000-square-foot monster with an outdoor bar and lounge, dance chamber, oxygen bar and a restaurant, Pearl set a new standard for excess in Tucson.

In July, Cusack debuted Zen Rock, where women perch on swings mounted to the ceiling and dance on stainless steel stripper polls. Zen Rock is on Congress Street in Tucson's downtown, only a block away from Sapphire.

More recently, Cusack's even gotten into the restaurant game. In December, he opened A Steak In The Neighborhood, a moderately priced steakhouse.

Now that Sapphire is open, the question is: what will Cusack do next?

"I've got some ideas, but they're still on the drawing board," he says.

If you go

Sapphire Lounge

• Where: 61 E. Congress St.

• Hours: 9 p.m.-2 a.m. Wednesdays through Saturdays.

• Cost: $5 Fridays and Saturdays. $3 Thursdays until 10 p.m., then $5. No cover on Wednesdays.

• Dress code: Dress shoes required. No shorts or hats. Jeans allowed. No baggy shirts.