Wow, thanks for the resources/suggestions all! Yep, there are an awful lot of possibilities. The plan, such as it is, is to spend a week + going from Minn. through Colorado, then 2 + weeks in Utah. Then whatever on the return home. So many choices, so little time.
Any advice for the return home? I'm unsure about mountain passes, and the potential for bad weather in Oct. If I push the trip more into October, then Utah may not be so hot. But we've been known to get blizzards near Halloween in Minn. I am thinking of taking the long way - across through Texas, and then straight up to Minn. Too cautious?