Nathan Richardson is quizzing me about the Concourse Athletic Club—a premier sports club in Atlanta. As President of Gilt City, he wants to know why the gym impressed me so much when I lived there as an undergrad. He has a vested interest in my answers.

That’s because today, Gilt City is launching in four new cities: Atlanta, Washington, D.C., Seattle, and Dallas. It’s Gilt City’s latest expansion since launching in September of 2010 as the fourth major brand offering under Gilt Groupe’s portfolio, which also includes Gilt Man and Jetsetter.

Deciding which cities to come to was as simple as looking at the math—and where members lived the richest lives, Richardson says. Gilt City, previously available in New York, Boston, Miami, Los Angeles, San Francisco, and Tokyo, already has over 1.8 million members worldwide according to the company’s internal figures. Wanting to build upon that strength, Richardson and his team of just over 100 employees combed member profiles as well as requests for Gilt City offerings to come to them. The leadership settled on the four cities because “we knew we could offer our 250,000 already-registered members in those four cities some truly unique experiences,” he says.

Gilt City's CEO Kevin Ryan adds, "By leveraging Gilt Groupe's loyal existing customer base, the trust we have built with our members, and our strong merchant relationships, we plan to capitalize on this momentum with continued expansion into great cities of the world."

And that’s where Gilt—Groupe, and its umbrella of brands—excels, in a marketplace that has become saturated with copycats and poseurs, says Sherif Mityas a partner in global management consulting firm A.T. Kearney’s retail practice, headquartered in Chicago.

“Where Gilt gets it right is by selling luxury—and more importantly, exclusivity—at a great price. And they do that by having the right relationships with the right vendors so that its members feel that they’ve locked up the luxury goods markets,” he says. “Gilt has nailed the perception that you can’t find the same value and brand on ideeli or RueLaLa. Whether it’s on a dress, or a man’s shirt, or now, a hotel room or dinner reservation, their expansion continues to support their luxury brand proposition.”

Richardson watches his competitors closely, even those in the coupon space, even though the two business models are vastly different. He's mildly entertained when others, especially in the lower-end try to emulate Gilt's offerings.

Having worked at Yahoo Finance with Mitch Spolan, who is now a senior vice president of national sales for LivingSocial, Richardson naturally keeps an eye on his former colleague who's now a rival, of sorts. Still, Richardson puts the competition in a very different category. "Because we're much smaller than a lot of the other companies that have popped up, we have the luxury of saying 'no' to vendors, we actively test whether a company fits in with our brand, and we can afford to be selective, unlike many of the other players," he says.

So far, investors have bought into Gilt Groupe’s overall vision, pouring $250 million into the company since it launched in November of 2007 (Gilt doesn’t break out investments per business unit). And as of May 9, when the company raised $138 million from heavyweights like Goldman Sachs and Softbank, its valuation rose to $1 billion.

Gilt City customers are high-end, according to its prospectus. Seventy percent have an average annual salary of more than $100,000; they’re young—66 percent are between the ages of 20 and 39; 70 percent are female; and 87 percent have at least a Bachelor’s degree.

Catering to a discerning and educated customer takes hard work, talent and attention to detail.

That’s where market lead and chief curator Sarah Sheehan comes in. Her job is to partner with potential vendors, vet them for compatibility with the company’s brand, work up an offer should they be deemed to fit the Gilt image, educate them on next steps, and hold their hand from the day their offer goes live on the site through the day the last customer redeems the deal.

“Most members don’t realize when they get our emails in their mailbox just how much work it takes to put an offer together,” Sheehan says.

What she’s most proud of is the innovation she sees.

“I approach every opportunity to deal with a vendor as a consulting meeting. I want to know what their needs are, what their best attributes are, and where we can help,” she says.

That can be especially true when dealing with a client like Bliss Spa, which doesn’t need any help bringing more people through their doors, yet has partnered with Gilt City twice and is planning offerings in at least one of the new cities just added to Gilt City's roster. “Bliss is a challenge because with them it’s about introducing new products or packaging their offerings in unique ways. It’s not about discounting their goods and services,” Sheehan explains.

Mike Indursky, president of Bliss acknowledges that he explored working with other flash sale sites but selected Gilt City because “we knew the Bliss brand would most resonate with the Gilt City member because Gilt has their finger on the pulse of the City. Their members look to them for that regional expertise.”

Giving clients and members specialized attention can be relatively easy when you’re a startup or an emerging business, but what happens when your company reaches the growth Gilt City hopes will happen with this expansion?

If done correctly, a company can scale up and its members and vendors shouldn’t notice the transition, says James Thomas, CEO of Itemize, a personal shopping site and deal aggregator based in New York City.

“Gilt started by selling in a manner that created buzz around high-end products that people wouldn’t normally have access to. With this growth, Gilt City has to remember not to get too outside of their strike zone. They have to stay true to their proven business model of bringing a great curated value to their members that is vetted just as well as it was in their other locations,” he says.

And in some ways, so long as Gilt keeps its expectations focused on the luxury market, the company shouldn’t plan to grow to 500 brands overnight, says Thomas. “You can’t be all things to all people, and Gilt, which has stayed true to its by-invitation model, seems to understand that. They’re not like the Groupons and LivingSocials of the retail world who are bumping along the bottom searching for the lowest price to offer to the maximum number of people,” he explains. “Gilt gets that shopping is more than acquiring a product at a given price point. That’s what Groupon is. So as Gilt City grows its brand it should keep in mind that the focus on quality, rather than quantity, is what will continue to differentiate it from the pack.”