SAN FRANCISCO – SeaTac-based Alaska Airlines celebrated its now completed merger Wednesday with Virgin America in Virgin’s home town.

It’s been nine months since the deal was first announced, and the combination gives Alaska Airlines much greater clout in California, creating the largest airline on the west coast.

Both companies will now make 1,200 daily flights to 118 destinations. After adding in partnerships involving foreign carriers such as Dubai-based Emirates, China’s Hainan Airlines, British Airways, Hong Kong-based Cathay Pacific, and Australia’s Quantas, the new company has links to 800 cities around the globe. Many of those international connections can be made at the mega airports of the Golden State.

While Alaska has long served California, Chief Executive Officer Brad Tilden says the Virgin American acquisition gives it a major boost in the west coast’s two biggest markets, San Francisco and Los Angeles.

“Virgin flies to eight of the top 10 cities,” said Tilden. “Immediately, we reach critical mass in the two biggest markets in California, and we have the chance … to be a go-to travel option for them.”

The merger makes the new company the fifth-largest airline in the country, and perhaps the last big merger in a trend that saw Delta take over Northwest, American buy up U.S. Airways, and United combine with Continental.

While Alaska Airlines and Virgin America are now one company, we don’t yet know if the merged company will become one seamless carrier or maintain two operations and two brands.

That fact is not lost on the new corporation, which clearly seems to celebrate the differences, at least for now.

Marketing language includes the phrase “different works.” In the seat back of an employee and media flight from Sea-Tac to San Francisco, the comparison is made to “electricity and guitars,” and “bacon and donuts,” combinations that might seem unusual at first, but seem to go together once tried.

The companies, both having received numerous awards for their customer service carry, but out that mission in very different ways. Alaska Airlines was born out of the state it was named for 84 years ago. Virgin America began flying just nine years ago as a U.S. majority-owned offshoot of British tycoon Richard Branson’s wide range of airlines ventures. It’s considered a bit of a “disruptor.”

Starting Monday, members of each airline’s mileage programs can get credit for miles earned on the other carrier.

The combined company will still be based just outside of Sea-Tac Airport. And Tilden says they will be embarking on an extensive program to find out what customers want. One airline or two? At a news conference to celebrate the merger at gate 54B, San Francisco media asked if the edginess of Virgin America’s product, such as ordering drinks and meals directly from your seat, would go away.

“That’s the question, and we said we’ll have an answer to that question in the next few months,” said Tilden during an earlier interview with KING 5. “That is the most critical item; is integration. Talking about getting it right.”