You can also do any segment. Having done Chicago to Emeryville, I'd suggest folks focus on the Denver to Salt Lake portion.
Chicago to Denver is mostly flat, and at least when I did it, mostly in the dark. Salt Lake to Reno is also boring, but surprisingly the section of rail around Tahoe doesn't have good views either. If you've driven on 80, or 50 or 89, you've seen better terrain.
As other comments have said though, the timeline is unpredictable, since freight takes priority. So you could easily end up in the dark around Grand Junction, CO and miss out on the views.
Chicago to Denver is mostly flat, and at least when I did it, mostly in the dark. Salt Lake to Reno is also boring, but surprisingly the section of rail around Tahoe doesn't have good views either. If you've driven on 80, or 50 or 89, you've seen better terrain.
As other comments have said though, the timeline is unpredictable, since freight takes priority. So you could easily end up in the dark around Grand Junction, CO and miss out on the views.