If you want to see long freights roll by, go to the Flagstaff station.
Think it's right downtown.
You can take a look ahead of time if you go to the virtual rail fan flagstaff youtube website. We stopped there on a trip to the Grand Canyon.
I know of some places in Durango like the Strater Hotel to see besides the trains but I am sure there are others and some museums. We will be staying in Pogosa halfway between the two railroads. We like real trains and great museums and unusual places to eat that are not tourist trade and not too expencive as we have a large crowd going with people of varius means. Also like some local venues and wife wants to go to a ghost town that stll accually is standing. Might go the whole route on both trains so we are talking about 4 towns plus Pogosa as the trains layover for two hours at the ends of each one. We are driving from California with a stopover in Flagstaff so Flagstaff stuff would help too.