My parents are traveling from Seattle to Denver on the Amtrak. The coast starlight comes into Sacramento at about 6:15am and they get off to change trains. Will they be able to get a quick breakfast in before getting off the Coast Starlight?
In a word, no. Generally speaking, breakfast isn't served until 6:30.
Furthermore, there is quite a bit of padding built into the Coast Starlight's schedule approaching Sacramento. Frequently the train arrives there well before 6 a.m., sometimes as much as 45 minutes in advance.
So unfortunately, the train would have to be running very, very late for your parents to be able to get breakfast on the Starlight.