Theres bears throughout all of western wa. From the ocean beaches to the Crest trail. Food sources in different areas will vary but by the middle to end of August its berry time. Lowland berries include blackberries, both Himalayas and native ones. These are usually found in and around clear cuts and along logging roads. Bears LOVE blackberries. Walk any logging road when berries are in and you will find purple bear crap on the roads full of berry seeds. Other lowland berries are huckleberries, salmon berries and elderberries. They prefer part sun, part shade usually. Most likely to find them along the edge of new clear cuts.
As you move higher the food sources change. Huckleberries and blueberries becomes primary food sources that time of year. Once you reach 3-4000' elevation the berries are all over the place, you just need to find the hillsides the bears are using.
Depending on where you are, I'd pick an area you can hunt frequently to maximize your chance of success. Bears are active throughout the day and evening in late August/September so going after work for a couple hours can be highly effective. I'd walk closed logging roads and glass clear cuts. Find the areas with the most bear crap and focus there.