The top four floors of the Cosmopolitan hotel in Las Vegas have been vacant since the day the casino opened in 2010. But as part of a five-year capital investment plan, they've finally been furnished and opened to the public.

Well, sort of. The 21 Boulevard Penthouse suites that now fill those top floors have balconies overlooking the Bellagio fountains and Vegas strip, designs by Adam Tihany, and $56,000 bottles of Louis XIII Black Pearl cognac — and a minimum buy-in of $1 million at the Reserve, the Cosmopolitan's high-roller lounge. That may make them the most expensive hotel rooms anywhere in the world.

The main driver here is to attract so-called whales. Before, those who wanted to play a million or more in the casino could go elsewhere and get more. "They were players and not stayers," explained Brian Benowitz, senior vice president of casino operations. "People play more where they sleep."

So what will those high rollers get now? We took a first look inside the Richmond Penthouse to get an idea.

About that price tag

In Vegas, a million-dollar buy-in isn't unheard of — at least not on big weekends such as the Super Bowl, Chinese New Year or New Year's Eve. But even the nicest rooms in town — such as the villas at Bellagio and the Mansions at the MGM Grand, where built-in massage rooms, indoor swimming pools and billiard rooms all can come inside the suite — are regularly available for far less money.

Ironically, managers of top Las Vegas suites have been dropping the high-roller requirement in recent years, opening them up to regular, nongambling guests — so long as they're able to pay. Sometimes these palatial rooms can go for as little as $5,000. Not bad, compared with the Cosmopolitan's buy-in.

"Our guests were telling us that even if they weren't in the casino, they wanted a villa experience, so we opened it up to anyone, and people love it," said Melissa Bailey, director of Sky Suites at MGM's 4,004-room Aria.

The value proposition

It's hard to argue that the Cosmopolitan's suites are "worth" their million-dollar price tag — particularly when the competitors offer a similar range of amenities. But if what you want is exclusivity and style (at any price), the Boulevard Suites will win your affections.

Here's what they promise: round-the-clock butler service, chauffeured airport transfers in a variety of luxury SUVs, and a full culinary team that will "create whatever our guests desire," said Benowitz. "If a guest wants stone crabs for dinner in their Penthouse, we'll go to Joe's and procure them."

Welcome amenities are selected based on each guest's preferences and could include a hard-to-find bottle of bourbon or a humidor full of their favorite cigars. Living-room walls are swapped for resin panels trimmed in 24-karat gold, and bathrooms have floor-to-ceiling marble and podlike soaking tubs. A white grand piano stands in the living room. And whereas Sin City's other megasuites all conform to kitschy themes, the Cosmopolitan's are worthy of the name.

The true cost of entrance

Not everyone gets in to the Boulevard Penthouses. To do so, you have to prove your net worth, clear a few security hurdles, and have paperwork submitted to the Gaming Commission — which gets you into the high-roller lounge called the Reserve, where you'll play your requisite million.

There are, and will be, exceptions to those rules — this is Vegas after all, where rules are meant to be broken. "Some of our slot guests don't have as much as a bankroll per individual trip but they come often, so their value is still very high," Benowitz said. "Anyone who spends over $100,000 on a given trip could be considered."

As for the 98 percent occupancy rates that most hotels in Vegas like to brag about? They don't apply here — which is to say, the Boulevard Penthouses will never be given away for next-to-nothing. "We're not overly concerned if a room goes vacant because there's an opportunity cost of getting someone in there," Benowitz said. "They're not at the same occupancy as the rest of the hotel, but on weekends? The demand is astronomical."