^^What Tom Tee said. Especially for the "traditional-size" trains you enumerate in the first post. Overpowering the layout goes for cars too. Personally I wouldn't buy anything larger than 1:50. Wider cars means wider roads, which eats into available space. Plasticville houses, roads, cars add realism and a sense of environment, but you can get more in a small space, and I like the focus to be on the trains.