Thanks to all for the great information. I did some research online about average temperatures for the times we would likely be at various legs of our journey. It all looks doable, so far.
Thanks, Ken, for your "insider" information. All the things you mentioned sound inviting.
Thank you, MarineByChoice, first for your service. I served in the Navy Dental Corps with the Marines at Camp Pendleton during the Viet Nam conflict. What an awe inspiring outfit. Second, thanks for the first hand information about weather where we are headed. We will be about a month later, so I am encouraged that we may find fair weather and lots of places to stay. I do share your affinity for sparsely populated state parks, though.
Gordon, I thought June might be early for Glacier NP. Thanks for your insight. I have heard of the Going to the Sun road, and seen pictures of GNP. I once skied at Big Mountain (decades ago), so I know the whole area is beautiful.
Once we are underway, I will post links to our travel blog, so y'all can go with us!!