Do your own thing. Kids love layouts with tunnels . They like to see the trains disappear then re-appear. Kids also like animations - flashing crossing signals, a gateman that jumps out of his shack when the train goes by, operating crossing gates, bubbling tubes in oil pumping accessories and the like. They like operating freight cars, too - log dumpers, animated box cars, etc.
Kids like to watch trains go around in the dark, too.
So light your buildings and make sure you have a lighted caboose on freights and at least one passenger set with illuminated cars. Kids also like steam engines - they like to see the drivers go around the wheels and they want to hear the whistle. And see the smoke. It's amazing to me that all kids love dinosaurs and steam engines. Both are extinct, so kids can't relate to the real thing.