You don't have to ride the entire California Zephyr route with Amtrak to get gorgeous views. Even just riding from Sacramento to Reno and back is the most magical experience.
I've been wanting to ride Amtrak for fun, and stumbled upon the California Zephyr from Sac to Reno which takes you through the Sierra. During winter, you get snowy views that transport you to another world.
Because this route is popular, you'll want to book ASAP or play around with departure dates to find prices that work for you. (Traveling in the middle of the week is likely more available than over a weekend.) I looked at fares about a month in advance and Coach had already been sold out, but Rooms may still be available.
Depending on the time you ride, there are various dining options. Small dogs and cats may also be able to come with you.
The California Zephyr route keeps going for those who want a cross-country train experience. Other top destinations it runs through are Salt Lake City, Denver, and Chicago. If you want the FULL experience, start in San Francisco.
Read more about amenities and features for the California Zephyr here.