Mike:
The Samoa Cookhouse sounds exactly like the type of place I was hoping someone would suggest, you see the "vision". Another place that comes to mind but I don't beleive is still in business was the Line Camp in Dolores, CO. It was a western BBQ served in a big tent and they had live music as well. We had the RGS 100th anniversary dinner there in 1991 if any of you attended that.
I really like the idea of making this building big enough to hold a trainload of people with meeting space for the Friends to gather, Commission meetings, Chama RR Festival, you name it. Including the RR museum and gift store could make it a "must stop" destination whether you ride the train or not.
If the food is good people will come for that and then "discover" the RR as well. With a simple menu and family "FRIENDly" style service you could target bus tour groups even offering a Cumbres turn meal and ride package or one way RR ride to the top of the hill and their bus picks them up and on they go or vice versa.
The key to any of this is to do your market research and then deliver what the customers want. The cheese is out there for the taking, we just need to be able to think outside the box it has been wrapped in.
Rod