WN still isn’t very strong in the Northwest so operating out of another airport in Seattle doesn’t make much sense.
WN is actually very strong in the PNW from a brand recognition standpoint.
From a market perspective, they used to be incredibly strong, however retreated after suspending their intra-PNW routes.
They used to do:
Recall that they originally had planned to serve PAE with flights to both OAK and LAS. I wouldn't be surprised if they eventually serve PAE one day.
RJ85, F70, E135, E140, E145, E70, E75, E90, CR2, CR7, CR9, 717, 732, 733, 734, 735, 73G, 738, 739, 744ER, 752, 753, 762, 772, 77E, 77W, 789, 319, 320, 321, 332, 333, 343, 359, 388