Twenty seven years ago, on my son's 2nd birthday, we started collecting trains with the intention of having a permanent layout in the basement. But, raising a family, working full time to support them, and moving 3 times all got in the way. Finally getting around to make some progress on the permanent layout goal. Late start probably kept me from some expensive mistakes, as our criteria evolved significantly along the way. Rather than stuffing as much track into every square inch, I think we would be happier with a reasonable and realistic mix of track, structures, and scenery. Working with some significant area limitations, and literally several hundred versions of the track plan later, off we go.
The lower track will be a folded dogbone of working track to operate (lot of switching, everything within easy reach), with an upper track around the perimeter to just run trains. Still working on the storyline, but basically the lower is a branch line serving local industries, while the upper is a two track mainline connecting the local to the world. One of the compromises I had to make was eliminating the grade connecting the two levels. With a realistic 2%, an 8" rise required over 33' of dedicated track, which would have taken a significant amount of real estate better utilized for other purposes in my little room. So we decided to simulate the interchange, with the offsetting gain more industry along the lower track itself.
Big thank you to members of the forum, a great learning tool and resource for us newbies.