You're coming at a good time. today I was walking at lunch without a coat. It's starting to get cool in the evenings and early morning. My suggestion is layer up. Tee shirt, sweat shirt and jacket. Jeans should be fine. Bring good walking shoes. there's lot to see here. I have lived in Seattle all my life and sister lives in Oregon. We can sure give you suggestion of what to see with your timeline. PM me if you want ideas or suggestions. Have a great trip.....