Portland is another big destination when traveling on the west coast. I've been there a couple times and there's plenty to do downtown. Portland is also big on breweries.
If you're driving South, definitely stop there if for no other reason than to get some food from the food trucks. There are tons of them and they have some pretty amazing food.
Also consider visiting Crater Lake on your way through Oregon. It's pretty far southeast though, so you have to be serious about visiting it. But it's a nice park and the lake is very unique.