mattbell

If you're going by Crater Lake (and thus spending some time through Oregon east of the Cascades), I highly recommend Lava Beds National Monument. It's a little bit out of the way, but only adds ~2 hours of driving after Shasta in northern CA. It's got lava tube caves you can walk through, neat volcanic landscapes, and the site of the last of America's Indian Wars, where a couple dozen Modoc warriors held off a few hundred US Army troops for over a year.