Popular Science solved the mystery of why kids get tired of model train sets: "Nine times out of 10 it is because the layout is on the floor. That's like putting glue on a fielder's mitt. You just can't play that way. Dad gets cricks in his back, Mom can't clean, track and rolling stock are stepped on, and Junior realizes that broadloom doesn't look much like scenery." Also, rugburn, guys.
If you want your child to really love you, you'll construct this table to house the trains. Also, to ensure that your kid actually plays with the thing you spent all this time making, and doesn't wander off to go to the movies, or eat, or something, build the table around him, as pictured here. If he still manages to escape, you could build a "control station" and put it over his head.
Read the full story in Electric Trains are Fun All Year.