I've been over to 2
LGS in Wenatchee. One of them, Cave Collectible Gaming (
https://www.facebook.com/pages/Cave-Collectible-Gaming/107659862609937 ) is a fairly small store with I think 1 or 2 gaming tables but decent space to move around in. I've stopped by a few times mostly to pick up paints and kits, I don't really plan to do much gaming but the staff are friendly. Never really seen many other people in there when I stop by but it could just be the hours I'm going in at, and I'm not there for very long.
Another one, GameSmith (
https://www.facebook.com/mygamesmith ) is a fairly bigger store with more rooms for gaming in, but I think they only have one table for
40k gaming, where as the rest is for Magic and other sorts of games. I chatted with the manager for a bit and he's also a friendly guy. Overall both places are pretty nice and inviting. I've only really checked them out briefly to pick up paint, but from what I've heard they both do tournaments/game nights and so forth.
AFAIK Warhammer isn't too popular out in this portion of Washington, so if you're looking to play a game your best bet may be to show up when they're doing a scheduled tournament, just check out their Facebook pages for when those may be.
Hope this helps.