Here is a great site for garages and shops.
GARAGE JOURNAL There are some great ideas, layouts, suggestions and more.
I can think of several things that I would do if starting from scratch:
Electrical: Use the largest panel you can get, set a sub panel at the opposite end to avoid running all of your wires to one panel. Choose panels that have quad breakers available for future expansion (Home depot has Square D Home) avoid this one. I like Siemens or Bryant.
See if 3 phase is available for lathes, large motors etc. Otherwise you will have to have a 3 phase converter power source 220 volt 30 - 50 amp depending on the equipment you will be operating.
Stub out at least one extra 3/4" pipe for future use after the walls are closed in. Leave one conduit outside of the floor plan for outside lighting, future well etc.
Install/loop conduit at each post to avoid having to drill through each stud to set your boxes. I like having three way switches at each door and this method makes it easy. All of this is under the slab and can be run in PVC in most jurisdictions.
Make sure you have marked out your locations for 220 V (compressors, welders etc.) I like having a 220V outlet at the front opening to allow for welding outside.
Stagger your circuits at your work benches so that you have more than one circuit feed the bench for multiple tool use. Remember to include at least one 220V outlet at your work station. Decide whether you want your outlets low or at bench height. The local jurisdiction will determine if you have to have your outlets @48" because they may believe that it is going to be used as an automotive shop and they want the outlets above the vapor line.
Set a couple of outlets high on the wall for beer signs, neons etc.
Carefully design your lighting so that all of the lights do not have to be on at one time, sometimes you only need minimal lighting when doing a small project.
Think about outside lighting and work lighting outside the shop. If you plan on having RV storage outside, consider lights an electrical hookup. Good time to add outlets for power washer, battery charger, tools etc.
Make sure you have additional empty conduits in locations for future lift, compressor etc. These should be dedicated runs, 3/4" or larger.
Think about future purchases, Big Screen TV, stereo, computer etc. Run communication/cable conduits to these locations.
If you are going to add a kitchen or some appliances, make sure you have enough power to add them.
I will add more later.
