I live in Vancouver as well. I've shot a few grouse this year within a 75 minute drive from Vancouver. Just go out onto public land and get off the main gravel roads and onto some of the old skids or gated roads that have gravel and are a touch over grown. Drive or walk... Get up high if you want the bigger birds. You really can't go wrong anywhere, but it's a bit tougher in the areas closer to town... I haven't had any success in the areas that are really close to Vancouver itself (the closer areas of the Yacolt Burn State Forest for example), but I have found them close to civilization just the same elsewhere as well as out in the most remote areas of the GPNF. It'll take time. When you're driving, drive VERY slow. They can be on the main roads as well. You'll find em' if you put in the time. The good and bad thing that I've found about grouse on the west side is that there is plenty of water, so they are everywhere... but then... that means they are everywhere, so the ol' find the right trees and water and you'll find loads of grouse is sort of shot, since the water is everywhere and really, I've found grouse in areas where there were Doug Fir only for miles and also in the alder stands.
TL;DR version: They are all over, but the lesser travelled and closed roads are your best bets, especially those up high and away from regular forest traffic.
