I think, it's the best direction. Even if you are going alone, upgrading on board to a roomette is usually worth the price because unlike in Europe all meals are included in the upgrade. If you traveling with a friend, the upgrade is a steal because unlike in Europe you always pay for the entire room, not per bed. For instance (typical pricing) an upgrade from conductor on CZ between Denver and Emerywille (S.F.) to the 2-bed small cabin ("roomette") will cost somewhere between $80 and $140 depending on luck, emptyness, constellation of stars etc. If you are together with someone, it's still the same price - for both of you. It includes 5 meals and if you are together - 10 meals in total. At $140 it's almost a joke. On the other side, a typical "2/3" sleeper supplement for roughly the same route length in Europe between Budapest and Moscow is in EUR 30 range and the "2/4" is somewhat less. EUR 50 for two is less, than $140, but you have to get the same five meals no matter what. At the end you will spend more in Europe than on Amtrak. Someone can argue, 2/4 is better than a roomette, but I like roomette better (more privacy). On the other side the 1/2 supplement is only about 1.5 times the 2/3 while the comaprable "de-luxe" room on Amtrak can be VERY expensive and (at least for me, I am a 'cheapskater') not worth the difference.
What is also true - and we experienced it at least in 50% of the time - having a group of people or esp. family (even a couple) helps to straighten things with conductors all over the world considerably. Try it with an airline with frustrated personal and security people under permanent stress...
Have fun and don't be sorry that the Coast Starlight is always very late. Bring enogh film because almost certainly you will catch Mount Shasta in the daylight. If you would go the other way, you probably will miss it.
