A lot of what's in this thread is still valid, https://pinside.com/pinball/forum/topic/seattle-bound. I recommend checking out 8-bit arcade in Renton, Seattle pinball museum at the international district, Jupiter and Shorty's near downtown and Add-a-ball in Fremont
Check out also skill shot (www.skill-shot.com) for a calendar of events (many, many) and a handy map on locations that have pins (also many, many)