Train sets I would like to see include a continuation of the Fallen Flags series.  There is a lot of possibilities for some really nice looking trains.

Second, some of past pasenger train sets had specific cars, super domes, dining cars duplexes that were issued in some road names and not others.  I would like to see the missing gaps filled in, e.g. Union Pacific Overland set needs the super dome. The Pullmand baby madison heavyweights could use a dining car, the combo baggage coach and so on.