My ideal garage would 60ft long x 50 ft deep.
50ft deep would handle my 41ft motorhome. Where the motorhome would be. I need a 14ft tall door, 12ft wide. I would need a 15ft ceiling. I would install a 120v, 50 amp hook-up, sewage drop, and water line on the left side of the motorhome. This way. I could hook-up the motorhome and live in it if I had to while parked in the garage.
This bay would be on the right side of the garage.
The rest of the garage. 2, 10ft x 10ft doors. 2, 40" wide man doors. 40" doors are so much better then the standard 36". I put one in my garage in the house. Between the garage and basement already.
Ceiling of 12ft. 1 twin post lift, and 1, Hunter 4 post alignment rack. Think the wiring would be 480volt coming in. That would handle any welder, Bridgeport, or lathe, 400 gal air compressor, etc. I would run metal pipe air lines everywhere. Including to the outside. The same with electrical outlets. Lighting would be everywhere. Would have 2, 8ftx4ft, 48" high tables made out out steel. The tops would be 1/2"thick. One 4ftx4ft, 48" high table with wheels on the bottom. one 4ftx4ft, 24" high table. This one is for tall things.
HVAC. Gas heat. Also would be a wood burning stove. Power goes out. At least I can cook on it. Have about 5 ceiling fans to move the air. Where I would be welding. Have a exhaust fan to the outside to remove the welding flumes.
This almost the same design I did for the power plant when we was building it. Minus the Hunter alignment rack, and wood burning stove.
And the little 4ton overhead crane.