Columbia River Gorge. Down south a bit but not real far. You could work this in on your up from or back to San Jose. At Hood River is the Western Antique Aeroplane and Automobile Museum at 4S2. This is not a collection of just a few planes and cars, there are hundreds and they are restored, not junk. The Gorge should be spectacular this year, wet winter, lots of runoff, the falls will be in their glory. Google Columbia river Gorge and the museum. At PAE is the Boeing tour. It's a good one. You may be staying close by and it's an easy drive but you can fly in to. There's a ramp out back, you go to the door, pick up the phone and someone comes down and lets you in the back door. Mount Saint Helens. It's a cool view to see a mountain that blew its top and went from 9677ft to 8363ft in a few seconds and the crater it left.
There is a forum like this one, pacificnorthwestflying.com. Register and tell them you're flying up and looking for things to do. It's not real active anymore but you'll get good local knowledge. There is a Facebook group called wings over the northwest or something like that. Ask about and find it if you do Facebook.
If the weather cooperates you are in for some spectacular flying. The Seattle area has it all, mountains, rivers, oceans, islands
