Coeur d'Alene to Craters of the Moon Route?

I lived in central Idaho for 20 years. If I had my "druthers" I would choose the route through Missoula if your main objective is to get to the Craters without doing any other sightseeing on the way. Don't get me wrong. There is a lot of interesting country on the 90/93 route, but you would only have to negotiate one city going that way. I don't know what the size of your rig is, but there isn't anything too terribly difficult about the route...just take your time on the passes.