I used 1X4's with grooves cut on my table saw for the flanges. A little stain and done cheaply. I also know several people have done like you are considering by adding shelves below the layout edges. I think Steamer Dave has several such shelves. They allow you to display more trains but you would need to allow for access to any designed storage behind them. They have been hung up in four different houses now and modified from being nine shelves tall to being five shelves tall based on my current situation. the way they are now situated allows me to display approximately 24 sets, but that depends on the sets individual lengths!
