Missed this one the first time.
There would be two options in my book and I90 would not factor into it for either option. That far north through the Rockies could be very bad. Beautiful but bad. The southern routes would be up through Portland on I80 or through bend on the highway 20. The choice being icy roads on Columbian Gorge or bad snow in the passes. Six of one half a dozen of the other if you ask me. I will probably go through Bend since it will at least be light out when I hit that part of the trip and it will be beautiful.