The Pacific NW Quilt Show is held in Tacoma now in August. It is held by the Association of Pacific West Quilters. They do have a challenge each year, check out their web site.
http://apwq.org/index.php
The MQX Expo is held in October at Portland, OR. Mostly for longarm quilters.
http://www.mqxshow.com/MQX/West/About/index.cfm There are some fantastic quilts to look at though.
The Sewing Expo is generally held in Puyallup as Roberto stated, but is held in March. It is a blast to attend and you can take classes there. I met Ricky Tims and watched his live show, totally worth it. Met Eleanor Burns as well. Lots of fun.
https://www.sewexpo.com/