I do have to ask if Dunkin' coffee is any good? I've never been a big coffee drinker.
No idea if the coffee is any good but around here their donuts are dry and tasteless. Instead of being made fresh daily like in the infamous commercials they're delivered by truck as circles of stale bread from some massive commercial factory somewhere. Kind of like Twinkies, only rounder.
Pretty generic. It's a smooth, easy drinking coffee. Not terribly offensive, but nothing that would impress a "specialty coffee" drinker. For the price I prefer McDonald's, since most locations sell any size for $1.
There's of course decent coffee available near Amtrak stations. I've boarded Amtrak with a cup from Peet's. If I'm willing to spend a bit more, maybe Blue Bottle. When Amtrak had a "station" next door to the San Francisco Ferry Building, there were excellent options for coffee.
Capitol Corridor uses Peerless Coffee from Oakland. I've been to their retail store in front of their roasting facility. The smell is pretty incredible. Even if you order tea or just hot water, they serve it in Peerless cups.
So why can't Amtrak serve Tim Hortons coffee?