If you decide to risk getting one or more Coach tickets and trying to buy Sleeping Car upgrades on-board, be sure to check
Amtrak's Weekly Specials, formerly known as "Rail Sale". With Lakeshore Limited (New York/Chicago) tickets going for as little as $41 each way and California Zephyr (Chicago/San Francisco Bay Area) tickets going for as little as $74 each way through mid-May at least, it may not be worth redeeming Amtrak Guest Rewards points for your trip. Weekly Special tickets must be bought online, with credit card, so it would seem that they are incompatible with travel vouchers.
On-board upgrade availability is hit-or-miss. You can eliminate the busiest trains in advance, by testing different dates on the
Amtrak Web site.
I've found upgrading on-board to be a hassle. One has to find a conductor, who has to look up the price in her manual and then fill out lots of paperwork. Train staff will not treat you as well as a confirmed Sleeping Car passenger, either.
When in California, remember that you can travel on our comprehensive network of state-funded Amtrak trains and Amtrak Thruway buses for just 1000 points each way. Since buses make up most of the network, you'll need a bus connection to go anywhere interesting. Some Guest Rewards agents will tell you that the bus connection is not included, but in fact it is. (The agent may have to put in a request to have the reward tickets issued manually, but it can be done.)
Enjoy your trip!
Paul Marcelin-Sampson
Santa Cruz, California, USA