I have attached big two car 25x22 with 9' wide 8' tall doors and a 20+' ceiling. Ah, yea my builder forgot the second floor back in '08. I'll be fixing that soon.
I also have a separate detached garage/shop that is 28x30. That garage has a 16x10' garage door and 12 foot ceilings.
Definitely use LED lighting, makes a huge difference in my working garage. Tall ceilings are great for loft and a Jeep hard top[emoji3]
P.S. no longer own an XJ but have used that XJADDICTION handle for almost 20 years. 2016 JKUHR stock, for now. This is my first JK and love it.