We had a similar thought when designing our layout. Many,many 1/64 Hot Wheels and etc. cars with no where to display them. I came up with the Garyville Motor Sports Park on the front area of the layout. Since I run an 027 layout and Plasticville buildings they don't really look too weird. This also gives small kids a front row view of both trains and slot cars.
I just took these pictures and you can see I have things apart today but you can get the idea of what I am trying to do.
Azgary