Sounds like snow is on the way so I'd take I-5 down to Vancouver, then pick up I-205 to east Portland where you can get on I-84. Take I-84 all the way eastern ID and then work your way to SLC. Be very careful around Pendleton and Baker City in eastern OR, the highway gets real slick there. Your best bet is to contact the Oregon DOT for info, they have excellent web sites. Am recommending going south to Portland rather than over Snoqualmie 'cause you won't have to worry about snow as much, at least for that portion of the trip. Do you need to take the Class A, seems like travel by car or whatever would be better at handling road conditions this time of the year.
