I want to share with my current rail layout, we have lots of fun on this.
We decided (with 6y son) to build instead of the classic one loop, two loops. At the beginning was a lot of fun, but continued running and change direction, by manual switch, spoil the fun a little bit .. we had to stop and maneuver ... That's why I came up with a pretty simple idea to build a track in such a way that would guarantee that the train would change direction automatically.... everything is a combination of a circle and number eight
this is a sketch of minimum rail layout. Arrows show directions on rail switch.
and the video, on a liitle bit customize and extended layout, for two person is great fun, because of risk of collision