Not done that particular route but have 'done' the Empire Builder 3 times in numerous directions each of which was about a 47 hour long trip.
The Dining Car is a great place to talk to your fellow passengers and, in our case, learn more about the people & places that make up the USA.
We love rail travel & are more than happy to sit & read in our bedroom, wander around the train & relax in the viewing car.
Staff on our journeys have always been polite & friendly & i would agree with the other posts about tipping.
We tipped $5pppn to our bedroom attendant & about 15-20% in the dining car which I was told is about right.
Have a great trip!