Definitely go to Sky Way Models when you are in the Seattle Area. One of the best selections of kits and prices I've ever seen.
Bridgetown Hobbies is also an excellent shop. If you are there Tuesday evening the local club Oregon Historical Modelers Society is having there monthly build night in the shop, they are very friendly group. There are some great modelers in that club that often post here on ML.
You may want to contact the Oregon Military Museum. It is currently closed to the public but you may check to see if you can make a private appointment. They have an excellent collection of uniforms, small arms, several vehicles and one of the finest collections of Japanese WWII equipment including a running Type-95 Ha Go.
Hope you have a great trip.