Avoid Seattle altogether. Unless you have to go there dont. Its become a sespool nearly as bad as San Francisco. There was an article just today in the news about SEA police quitting in droves. On top of that traffic is absolutely horrible. But Mt Ranier, Mt St Helens, Grande Coulee dam are worth visits. Grande Coulee has lasar light shows during the summer. From Grande Coulee you should head SW toward the Oregon coast. But again be aware parks on the coast will be booked solid, so probably not a good place to visit. In fact, camping in the far west is super busy this time of year.
