Hello. The first rule is "Plan, Plan, Plan". It delays the build, but helps avoid design mistakes.
There's a lot of debate about "around the walls" vs. "Island" type layouts.
Around the walls layouts allow for the best access and better viewing because you can only see part of the layout within your field of view. It also allows for wider curves. It comes at the expense of depth -- usually 24" to 32" is about the maximum for your benchwork. You also need a duck-under or lift-out bridge section to access the interior of the room/layout. I'm currently working on several 12'x12' designs for an anticipated relocation in a few months. This one has 42" radius (O-84) minimum on the curves and will handle any piece of equipment I currently have. The lift-out is at the lower left.
The "Island" type yields a bit more space for accessories, but creates a reach problem if placed against a wall or an aisle problem if placed in the middle of the room. It also limits your curves to the width of the table less six to eight inches. Here's an earlier concept I had worked on several years ago. It's 10'8" x 7' and the buildings were placed in the interior in such a way as to prevent seeing through to the other side of the layout when viewing from track level. It featured 36" radius (O-72) curves.
Hope this helps.
