I've been looking at TS2012, and the simulator seems to be pretty limited. It only has 3 routes, and the terrain comes pre-textured when you try to build a route. I think you can add textures, but I don't have info on that.
One feature I like is the use of Google Maps directly in the game to lay out track and terrain. It would be a fast way to lay out your favorite system, including long discontinued routes if the right of way is still visible.