I've done the Canadian in sleeper class both ways across from Toronto to Vancouver a few times. It's pretty affordable if you get a berth, and book from the via rail "deals" website. The food is top notch, but it starts to get a bit boring after while on the four day trip. I would recommend just going from Winnipeg or Edmonton to Vancouver or vice versa.

I also really enjoyed the Coast Starlight (SEA-SFO) (was unlucky enough not to get a Pacific Parlour Car), and the Empire Builder (SEA - CHI) is a great trip as well. It's too bad that Amtrak removed the wine tasting though.