This is a layout I help build for a new club member. It's in a small area of the downstairs finished basement. There was enough room for two 4 X 8 tables arranged in an 'L" with only about 2ft walkway on three sides. The member had a MTH Blue Comet Standard gauge in a water damaged box and a G gauge engine with a couple cars. The challenge was to get them both on the same table, also add some O gauge and HO track.
Here is a video of one of the first runs.