I found a video on youtube which I think is very nice and worth a look.
Trains on Location: Cascade Crossing
It's a 1 hour professional documentary from 1993-1995 showing the old SP batteling the Cascade Mountains of Oregon.
You know the route as UP's Cascade Sub or as the amazing Wilamette Pass for Railworks.
There is a lot of SP EMD power and a snowy landscape to see.
"Also climb aboard Amtrak's eastbound Coast Starlight #14 just west of Crescent Lake for an eastbound winter cab ride down the hill from Cascade Summit to Oakridge during the last 15 minutes. Kevin P. Keefe narrates."
All on youtube: http://www.youtube.com/watch?v=NJVpBiSpY0o&feature=channel_video_title