George, here's a comparison of how an around-the-walls plan compares to an L-shaped one. The stairs land toward the bottom of the diagram.
A couple things I don't like about going around the walls - the S curve (too tight for big steam and scale length passenger cars) and the loss of non-layout floor space for hanging out. I am intrigued by the photo potential for the roundhouse. I'm also concerned that the space along the west (left) wall is too tight for yars/sidings etc.
