I have 12' ceilings and a 10' door opening, which accomodate everything I had in the last year. Will also tolerate most vehicles on an anticipated 48" scissor lift. My shop is 25' x 42' =1100sf. About 25' x12' (300sf) is for the Wash Bay. I'd make the shop 30' wide (5' additional). That would allow TWO Suburbans side by side, with just enough room to work.
I wish I had:
More space!
Additional overhead door (drive thru).
More HVAC capacity.
Retractable overhead electric.
Daylight! (Windows/skylights)
More Space.
Even though you may not be washing cars, you'll still want a center floor drain, with flat floors sloping to it.
Dedicated 20 amp circuits (with GFI) for the Air compressor, pressure washer, and extractor. My Century 400 Sensei needs TWO 20 amp circuits!
Even more lighting! at least some of it should be portable. Use ceiling-mount Metal Halide lights if at all possible. A combination of fluorescents and halogens on the walls at about 36".
Give careful consideration to the colors used in the shop!
Have you seen my
Gallery ? BTW, I've added $600 in add'l wall lighting since those photos!
Lots more!
Jim
Oh, BTW, a year into your project, you'll wish you had more space!