My family of four (Me,wife and two boys, 11 & 17)want to take a circular car trip from the Seattle area east and south. I'm thinking as far east as central Montana and as far south as northern California.
We have about two weeks and would like to do some non-primitive tent camping mixed in with cheap lodging. We like history, geology, and some anthropology (e.g. petroglyphs, digs, etc.) I'd love to see some authentically historical sites that put me in touch with life as it was lived 50 or more years ago (for example, we loved the Virginia City cemetery).
Can anyone suggest a route that would take us through some interesting spots, or just identify some cool spots that you wouldn't miss if you were going?

Thanks