From a customer standpoint, the first Amtrak station in SLC, the UP station, was the best. The Rio Grande + Western Pacific station was second best. The worst is what they have now, following the St. Louis precedent of "temporary" facilities. When we conducted the 2008 ColoRail Pioneer station expedition, Salt Lake City was already temporary.
On a later occasion when Greyhound's PDX<>DEN two-night/one-day run was annulled in SLC due to weather delays, I switched to the CZ. While several of us tried to sleep in the Amtrak waiting room, a guy came in off the street, switched on the tv, channel surfed, found nothing, and walked out, with the tv still on.
On another occasion in the street near the "temporary" station, I had a nice conversation with a fellow who was homeless in SLC as a break from being homeless in DEN. We knew a lot of the same places in my home city of Denver, for different reasons.