The Doubletree across the street from the airport offers a cruise special periodically, which includes a shuttle to the port. Nice hotel too - but huge. It was a several minutes walk from our room to the lobby. Good restaurants and free wi-fi in the lobby.
However they don't provide return transportation from the pier to the airport. There is a very efficient shuttle and taxi service at the pier. We had reserved a limo with them but there really was no need. We could have bought bus tickets right there and stepped aboard and been off to SEA in minutes. Instead we had to wait for our limo.