I was active in the hobby and bought a lot of stuff 17 years ago and then devoted all time to hot rod cars. Now 67 and back in the hobby. My layout is in my living room 88 sq. feet. Two loops one go's up and over the other. Also a reverse loop and a 4 track small yard with a short yard lead. 110' of track. It's Gargraves with Ross switches that are on the mainlines and Gargraves switches for the rest. There is a crossover so a train on one loop can go over to the other and then into the reverse or the yard. Grades are 3/8' to 1' and 1/4" to1'  18" radius and 19" radius. I drew a scale track plan and made the layout from that. One loop is operational 9/10 and roadbed is done waiting for track. It is open grid L girder.