I was at discount tire yesterday getting the tires at on the DD balanced. I looked at their shop and their space. They had four garage doors and TONS of space to do work. If I was building a shop, I'd start looking at commercial shops like that to get an idea of how much space they budget per vehicle.
Also I would have a large room in the back for custom builds/restoration/etc. A dedicated spot for long term projects. Keep the bays up front for oil changes, swap tires, week long projects only, etc.
I painted my garage floor. IT IS AWESOME AND AMAZING. I recommend it. All I did was I went to Lowes and bought the kit. I recommend buying the kit, then reading the instructions. Then you know what else you need to buy. Also it is a long, drawn out process. Takes a while to do everything (prep + drying) so do it before you move in. Also get you at least 2 box fans for drying after prep. Lastly you can add non-skid to the paint. YOU WANT THIS.
An upstairs-loft type setup for BS parts/camping gear would be clutch.
Currently for my garage, I am going to build my work bench and enclose my air compressor underneath it with sound insulation. I also have everything I need to run air lines in my garage as well as a hose reel. That way my air compressor can run without pissing me off or the neighbors and I can have all the air I want.
On that note, drop lights and power plugs on reels are also pretty badass.
Wood burning stove. You can understand this.
As for lift, look for mid-lifts. 2 post and will raise it 48". Ok it isn't a BAMF 4 post lift but you can raise it up enough to get underneath the rig while you are on one of those rolling work chairs. Also some are portable so you can unbolt it from the floor and move it out of the way when you don't need it. I'm considering one of these. Would be super handy for working on the rig or changing the oil/brakes on the DD.
Overall, that is pretty much my ideal shop. However right now I have a 2 car under my house with a small work area so most of this I won't ever have. However there are tons of small things I've mentioned that'll make life a lot easier!!