If we're going off of highway regions, ND and MT only have the Empire Builder line, WY has nothing, and Colorado has a couple Amtrak lines, RTD in Denver, and some tourist railroads.
If we're willing to move off of that, I'd be willing to draft the SLC and Denver rail networks (since I have a little experience with those), the Colorado tourist railroads, plus some other short lines that I know fairly well (Old Hill City railroad in SD, KCMO streetcar), but I don't want to step on anyone's toes.