I've gone cross-country on Amtrak, and being poor, I couldn't afford a sleeper. 2 and a half days from Seattle to Chicago in a partially reclining seat was pure misery.
I'll give points for the scenery, though.
Well, except for North Dakota at night.
Not much better in daytime.
Like I said in my post, if you have to go a long distance and you have the time, it is pretty economical. The cost of the 30-day rail pass was about $400 and the cost of the sleeper was about $100/day ...
Unfortunately, SEA-MT is not a long distance - even round trip ...
In January 2012, I rode the Empire Builder MSP-SEA for $132, one way. It took 37 hours then, but now takes 40 hours.