Many articles about the California Zephyr, for example: Catching the slow train to Frisco for a glimpse of America's pioneering spirit described that the author made several stops (like 24-hour) stops in several places in the middle of the trip.
You could make the whole trip in two days and two nights if you wanted. I planned to hop off for 24-hour whistlestops in three places. I would strike out across the prairies of Iowa and Nebraska before overnighting at the little town of Granby in Colorado's Middle Park Area. After snaking though the Rockies, I would stop at Reno, Nevada, for the nearby Wild West mining town of Virginia City. Finally, I would overnight in Sacramento, California's unheralded little state capital
What is the cost-efficient way of making such arrangement? I checked the Amtrak website, and I can book "multi-city tickets" from Emeryville, CA to Glenwood Springs, CO and Glenwood Springs to Chicago, but it seems to be considered as two separate tickets, and is much more expensive than direct Emeryville-Chicago ticket.