I'm moving to Seattle next month and super bummed I'm missing this
There's plenty of other nerdy things here :p (Emerald City ComiCon, PAX prime, Seattle Retro Gaming Expo, GeekGirlCon, &c &c &c)
Someone at VCF PNW handed me a business card for the Seattle Retro-Computing Society, which has monthly meetings over on the east side.
Also have to admit I'd been wanting to see the MOnSter 6502 in person since I initially read about it. Glad to have finally gotten to.