Well, I am a little disappointed, since I don't have a standard gauge track library.
That being said, I found that there were no layout plan books and such accumulated.
I think the same concepts apply to these large trains. One observation that I did make researching layouts, was that second and third layers were used to make the most of space. One was really appealing as the train traveled through a mountain 4 times on a trip on an elevated section just for that train.
The older designs that I did find, made use of 3 switch wyes and reversing loops inside of the outer oval.
By the time model railroad publications came about, Lionel had moved on from Std. gauge. Most collectors focused on their engine and car finds and not documenting surviving layouts.
So, it's wide open to find the best way to show off these beauties and highlight any structures that you have within the plan.
I'll try some shapes that will leave room for the actual track.