Seattle-Tacoma International Airport is about to get a serious upgrade for premium travellers. Chase has proposed a 16,000-square-foot Sapphire Lounge near Gate A11 in Concourse A, and the Port of Seattle was scheduled to vote on a 15-year lease for the project at its September 22 meeting. If approved, Chase would pour roughly $70 million into construction and a later refurbishment — a big bet on the Pacific Northwest's busiest gateway.

The new lounge is nearly three times the size of the existing Club at SEA facility it will replace, which covers about 6,100 square feet. Rather than a simple facelift, renderings submitted to the port show a purpose-built space with multiple seating zones, dining and bar areas, workspaces, and quiet corners for passengers who want to relax before a flight. The airport, meanwhile, stands to earn around $7.9 million a year in rent, starting at $500 per square foot, with 10% bumps scheduled in years six and eleven.

Here's the catch: the Sapphire Lounge can't open until a chain of other moves plays out first. United Airlines is building a new club in the former American Express Centurion Lounge space, complete with a second level. Once United relocates, The Club at SEA is expected to slide into United's old Concourse A spot, freeing up its current location — plus previously earmarked expansion space — for Chase.

The location is no accident. Gate A11 sits at the far end of Concourse A, right next to Delta's lounge complex, including its upscale Delta One Lounge. That corner of the airport is becoming SEA's premium hub, and Chase clearly wants in. It also fills a gap on the West Coast: Chase already runs Sapphire Lounges in Boston, Dallas, Las Vegas, New York, Philadelphia, Phoenix, San Diego and Washington, with Los Angeles and Miami in the works — but nothing in the Pacific Northwest until now.

So who actually gets in? Access to Chase Sapphire Lounges comes with the Chase Sapphire Reserve, J.P. Morgan Reserve and Ritz-Carlton cards, and many Chase cards also include Priority Pass Select memberships. Worth noting: The Club at SEA's current Concourse A location is already Priority Pass-accessible, so members aren't losing out during the transition — they'll just eventually get a much bigger space. Don't book a trip around it yet, though. Because the opening depends on the wider lounge shuffle, there's no firm date. Travellers departing from other concourses should also factor in the walk or train ride to Concourse A.

For anyone flying through Seattle with a Sapphire Reserve in their wallet, this turns an existing card perk into a dedicated, full-size lounge at a major international hub — one more reason the credit-card lounge race is heating up at airports across the country.