72° -still!- was supposed to drop into the fifties. Had a good and quick thundershower in the evening.
Looks like you could drive I 90 from Seattle and catch I 25 at Buffalo to return to Casper and avoid Tacoma. Unless you like to explore more driving through the smaller towns.
A friend wanted to go to the Boeing factory tour some years ago and wanted me to come up with a route, would stay in Kirkland see the factory then ride East to Lolo pass and then catch US 93 through Idaho back to I 80 in Wells before returning to where I used to live.