Hi Jake,
With respect to the Cumbres & Toltec, I believe that the Friends have already announced a couple of trips, one of which is in June and one during fall colors. Look here:
Friends Charter Page
It is possible that private operators may organize other trips on the C&TS, some of which may be announced publicly, while others will only be announced to private client lists. All you can do there is watch the message boards and get your names on the mailing lists of other charter operators.
With respect to the D&S, they do offer both Fall and Winter Photo Trains. Look at the D&S Events page for those.
D&S Events
/Kevin Madore