This. We have a 60x80 building with one and it's great. We have stuff stored on top and even some stuff hanging from the under side. The bathroom is in the same corner, roof for that is part of the mezzanine. It's also helpful we have forks for our tractor and can put some pretty big stuff up there (made on section of the railing able to be swung open)
The place we purchased, the garage was not insulated and has two 10Wx12H metal doors in front and 12x12 opening with double sliding doors in back. Sliding doors are the pits very difficult to seal from weather or bugs.
I looked at insulated roll up door to seal the back. The door salesman talked me out of the insulated roll up door. He stated a standard insulated metal door would work better and be cheaper. Plus the insulation on the roll up door will come off. The insulation is glued on the roll up door and every time you roll it up you damage the insulation and glue. I ended up installing 1/2 insulated board in the door panels on the front doors and sealed the sliding doors the best I could.
Plus the aesthetics you can get with the standard sectional metal garage doors is amazing. You can get almost any R-value you want. Someone mentioned it previously go to garage journal site you can get some great ideas about every aspect of the build.
The garage I had the walls insulated and sheathed with 1/2 osb. By using osb you don’t have to worry about always having to find a stud to attach something to the wall. Plus spray insulation In the ceiling.
The walls are not the prettiest however they are functional which is what I wanted.
Consider a washer dryer, nice to toss what ever the heck you want in there, with out the Mrs looking like "WTF are you doing"..... I was also going to say a shower, but your house is close enough.
We did one last spring Nick. You can pm/email/call me if you want to talk. We learned a ton. I did all the electrical. We love it but there were a few things with our contractor that were a huge PITA. Plus I get to finally park my truck inside!
Edit - use this to plan your layout. I used it because I was capped on size by the county and wanted to fit cobra, boat, and truck. Shop Tools and Machinery at Grizzly.com