Many thanks to all of you, now I have a better idea what the convention is. I was not aware about the home layouts not to be at the convention site and about the clinics (I translated clinics first with "hospital", I thought this would have been a first aid room...). But from what I understand now, clinics is more or less similar to workshops.
I will attend the 2-day RGS charter on the C&TS, so after the convention I will head towards Antonito, and from there we will continue nature- and sightseeing in NM and CO (my wife needs to be pleased also). I'm not sure if we will ride the D&S again, we visited Colorado already a bit more than 1 year ago, when we did all the regular train rides already. Only on the Georgetown Loop we were not lucky with steam, I hope to see steam there this year when we try again.