[dsraven]

with a 12 ft cieling you have the opportunity to have shelves "hung" from the rafters around the outside walls. that way stuff is up off the floor but still accessible from the shop with a step ladder. plastic bins or "milk crate" style boxes work well and also stack. the "hung" shelves still allow the vehicle doors to open and not hit a floor mounted shelf unit but still allow lots of accessible storage. being taller off the floor allows more room around the vehicle as well.
-I have a step ladder with the back beams missing so it simply leans against the "hung" shelves. the "paint tray" or top step is deeper so it actually sits on the shelf for stability and also gives the correct climbing angle. it is also light and smaller so it easily stores on a set of hooks below the shelves.
-under those shelves I have installed some 45 degree angle brackets that hold 4 ft fluorescent fixtures with screens so the light is scattered out into the shop area instead of straight down at the floor. the lights are closer to the floor than yours would possibly be, due to ceiling height, so they get light under the overhang of a fender when doing jobs like brakes or shocks etc. good light = less mobile lighting that usually ends up being a pain. they don't call them trouble lights for nothing. it's because they are trouble.
-since I use my shop for a repair facility I rarely park in there. it is usually full of projects or "jobs". with that in mind I have figured out where to have air line drops with hose reels for the solvent cleaning tank, the workbench, one on each outside wall in the middle of the work area, one longer reel in the center of the 2 bays, one plug in at the post between the shop doors. I have a plumbed in coiled airline near the solvent tank/workbench so a hose reel is not taken up with a tool that is used a lot in these areas. not always unplugging a tool and plugging in a blower, then reversing the procedure to use the tool again.
-I have left room near the compressor for some large copper line that is looped and sloped and has a drain at the bottom. this is an air cooler from the compressor outlet so air can cool and drop out moisture before it heads to the next, shorter moisture elimination unit sitting closer to the compressor. if I were doing it again I may try to use some "fin" from a heating unit. it is copper line with fins on the outside for radiator style baseboard heaters and would cool the tubing better than simple smooth copper line.
-from there the air heads out to the large air lines that run across the ceiling to the hose reels. at each end of each of those there is also a drop out, below the air line take off, with a drain for condensate. some have smaller plastic line run from the steel piping low point which runs down to an accessible area for easy draining.
-on my compressor I have an electric auto drain unit that is tied to a light switch so the compressor tank gets purged regularly when I am in the shop (lights on). this is because I regularly forget to drain the lines in the morning. so far the system works well with basically zero noticable moisture if I were to blow air with a nozzle. tools get less wear this way.
-personally I have steel line but lots of guys are using plastic plumbing, like pex, and have no issues. when I did mine the supplier couldn't tell me if the pex fittings would hold 120 lbs of air. pex makes it quite easy since you don't have to thread stuff together.cut, install the fitting, crimp, carry on. the plastic doesn't rust and is way lighter. run large lines, like 3/4 or 1", so your tools receive enough pressure and will work properly. large lines are also an air reservoir.
-place a valve near the compressor so you can disconnect the compressor quickly if need be if you blow a line or whatever.
-it is nice to have a hose reel near the work bench vice but put it far enough away, overhead, so the hose isn't hanging in the vice jaws while you are working or using a torch or whatever.
-if using radiant heaters remember it heats up darker objects quicker, like possibly your forehead if the heater is placed above the workbench, so if you are a hat wearer or use a welder's cap it could get warm on the head as the shop heats up. personally I used an overhead unit heater for that reason and also because it gets cold (like -30 C) here so when the doors open the radiant heat takes longer to warm things up. floor heat is nice as well but takes more time to install plus the expense of the install, maintenance and the worry of what a cracked slab could do to the lines in the slab or what would happen should you want to drill into the floor to install a hoist, tire machine etc.
-whatever you do, take pics of where things are before you insulate or sheet the walls. then you know where stuff is later if you want to install a shelf or something later.
-for wiring, if you plan on electric door openers, a light switch that cuts power easily to the shop doors makes it easy to disable the shop doors without dumping the breaker so the breaker doesn't wear out over time. it also makes it harder for a thief to power up the door openers, should that scenario ever come up, because they don't know about the switch.
-run another door bell switch to the big doors so you can open/close the doors from the big door area without punching a code or carrying a remote.
- if doing it again I would also install a conduit from the breaker panel area to the attic area so if I needed to run power to something later it would be easier.
-office lateral filing cabinets make nice tool storage areas for grinders, drills, or other large tools. the shelves work like drawers for easy access and the shelves have fronts so visitors or passersby don't see what tools you have. unlike permanent shelving screwed to the wall, they can be moved wherever you like and also can be placed on rubber strips so if the floor gets wet often they won't rust or rot (like wooden shelving). they also have that top area for big stuff like chop saws or tote boxes.
-for a workbench I went to the local scrap metal dealer and managed to find a good sized chunk of 1/2" plate. I had it cut to size with nice square edges and then mounted it on a base made from good sized pipe. I made a shelf under it with steel shelving for the actual shelf and reinforced the edges with some good stout flat bar under the top. I sheeted in 3 sides so things on the shelf only get dirty from one side. on the shelf I keep my jack stands. if I am cutting or grinding the stands don't care but they also don't get too full of slag etc.
on one of the front legs I have installed a horizontal pipe that accepts my engine stand part. there is also a square tube near the floor of that leg that accepts a piece of square tube that acts as the lower extension of the engine stand so the bench doesn't fall over with a heavy engine.
the vice is bolted on so the inner jaw is even with the edge of the workbench so I am able to hang something in the vice and have it clear the front edge of the bench.
the tube installed in the leg for the engine stand also doubles as a place to install a table top "extender" so if doing something like u joints, where I need to support the end of the shaft while the other end is in the vice, that extender makes it easier.
on the other end of the bench from the vice I fabbed up a sheet metal break for bending smaller items, the width of the workbench.
hope it helps. if I think of other suggestions I'll let you know