Well here's what has been going on here as far trains/train layout. The garage is fully closed in and the door to the house is waiting to be done. It will be one of those barn type that slide from one end to the other, instead of opening in to you. The layout is built as far as framework and the plywood top. ( 3/4" ) I put carpet down on top but have not yet gotten to fastening it down. ( plan to use carpet tape. ) I have 4' metal shelves under it and have built some wooden ones also. And I'm still running out of room where to put everything. I plan on adding another 12' x 10' onto the 16' x 12' I already have. the 12 side will meet up to the 16' side of already built. Leaving me about 4' x 10' for small 4' x 4' platform where the door is and then 2 or 3 steps down or maybe a ramp to help wife to get up and down, if there is enough room between the platform and the door to the outside from that room. trying to decide if I want to do away with that door or not as it will not really be needed.
As for design I have not yet figured that one out. I presently have a 24" turntable and a transfer table with one extension. I'm using O gauge track and have O31 up to O96 in curves. I have 24 30" pieces and about 300 10" pieces of straights. I also have about 24 O22 switches, five 90 crossovers and three 45 ( I think they are called) At present I'm thinking of putting both transfer and turntable on the 10' x 12' extension I plan adding somehow. There should be plenty of room to do so. Right now the largest turn radius I need I believe is O54 and that's for my Atlas 33,000 GL tank cars.
My main objective at present is getting all the trains under the train table or on shelves. Then the door to the main house ( the garage was a add on some time before I got here and they never put a door between the house and the garage. I'm tired of going out the back door to get to the garage/train room.
I do plan at the far back corner putting another 4' x 8' sheet of plywood and put my Lima 2 rail O scale train set on that. I will fill in from the board ends to the walls so it looks like a big area. I will put my model power buildings up there seeing there so much smaller than the Menards buildings I have, to give it the far away look. I hope to build between the two levels which looks like either mountain sides or hill sides anyway.