A few paces that spring instantly to mind are Olympic NP, Mount Ranier, Portland and the Columbia river Gorge, Mount Hood, Crater Lake and the Oregon coast, possibly the Redwoods on the Cali coast. This could make a nice loop trip and if you were to travel the coast it's best to do so when heading south so that the ocean is on your side of the road. As Michael mentioned, Yellowstone is an option and quite an amazing place that would deserve at least 2 or 3 days of your time. The Grand Tetons and Glacier NP are two other places you could include in this area. There are lots of other great options for you to consider, so as Michael also mentioned, do your research and see what appeals and then we can be of more help.