sbm,
You are most certainly getting the same views with either train as they follow exactly the same routing. About the only advantage that the Coast Starlight has on the view is the fact that it offers a Sightseer Lounge car giving you bigger windows to see things.
If you do decide to opt for the CS, definately do it southbound. While things have improved considerably from a few years ago, it is still possible for the northbound to run late, which could kill your window of opportunity to even ride.
I'm also not sure that I'd call it one of the most scenic rides Amtrak has, but it is a very good one. But the Coast Starlight offers much better views further south in the mountains of Oregon and on the coast down in California.
As for business class, I don't know that I'd run away from considering that. You would get a single seat to yourself, you do get a $3 voucher to use in the cafe, and perhaps most important you have a much shorter check in line and you'll board first ahead of the coach passengers. IMHO not standing in a line of 20 people to get my seat assignment is well worth the few extra bucks for business.