Hi 750, the best vintage/cafe/custom event is monthly, Backfire Moto Night, in ballard, they get 300 bikes on summer months, and I've met up with other DTT-ers there:
http://www.backfiremoto.com/
The VME is has monthly meetings with old iron and runs the amazing Vashon TT in summer:
http://vmemc.org/
Seattle Cretins does events, rides, drinking contests:
http://cretins.org/
Twinline is a custom shop thats like a clubhouse, go bring them beer and hang out:
http://new.twinlinemotorcycles.com/
welcome to the scene!