A basic "think about it" for any newby planning to build.
One of the biggest concerns in building a layout is sharp curves and short tangents.
It is an undisputable fact that any island style platform layout will have shorter straight-a-ways, sharper curves and occupy a greater portion of any train room than what else could be built in the same area with an around the wall style layout.
If at all possible or practical, an around the room layout will also provide a larger congregating central area.
Just consider it.........especially if your interest is large locomotives, long passenger cars, long freight trains.
