My volunteer fire dept built a station 18 years ago and installed radiant floor heat at that time, and to this day it's still one of the best decisions made. If I ever build myself a shop you can damn well guarantee I will do the same thing. Spend the extra bucks and put insulation in the walls and ceiling. Even if you dont think you need it, do it anyways- insulation is cheap. You'll hold the heat in the winter and help to keep it cool in the summer. A good industrial air compressor, a couple'a heavy work benches (with a good sized grinder and a drill press) and a good sized parts washer are absolutely a necessity. As someone else said, be sure to incorporate some kind of heavy steel into the framing so that you can use chain or grip hoists to do heavy lifting. A bathroom with a shower and a deep/slop sink would be very nice to have, if you do incorporate plumbing make sure you put a washing machine into the plumbing calculations- then you wont annoy the wife when you wash the shop rags in the clothes washer/dryer in the house. (whistles innocently.....) An would be an office to do your paperwork, search the interwebs for pictures of Winfall Wimmim errrrr ahhhh I mean needed parts........making phone calls, a place to keep your manuals and books.......If I ever build a shop it's gonna have a second floor which will be for the no-wimmim allowed man-cave. Good to have: A good sized sandblasting/glass beading cabinet And, I wouldn't be doing my civic duty as a firefighter if I did not recommend that you install an NFPA-compliant sprinkler system. Protect yourself and your investments from fire!!!