What would you do differently if you were setting up your shop?

[Wild Turkey]

If I were doing it over:

More lights.  If it's too bright you can turn a few off.
More/bigger windows.  I found some double-pane on Craigslist and wish I had more.
Careful siting.  I was forced to put it where I did; I wish I had more Southern exposure.
Big enough roll-up doors.  8 and 10 feet wide are too small. One on each end for cross-flow breeze (and the occasional leaf-blower dust removal)
Walk-in doors where I will walk; not where they were in my last shop.
(backstory-- I assumed my woodworking would be on right wall and welding/mechanic on left.  Swapping layout makes a lot more sense but now door is on far side.  Nice when I drive up in pickup, not so good when I go down from house)
More outlets.  I put duplex 110 v every 8' (54" from floor) and 220v every 16 feet.  4' and 8' would be better, quad instead of duplex.
"Off-delay" timer on exterior light.  In the winter when I leave it's dark and I can't see where I'm walking; timer on driveway floodlight would solve that problem.

I put OSB on studs after insulation/wiring.  I used screws and fender washers so walls are secure.  Two coats of white enamel makes it lighter and doesn't hold dust as bad.

Good luck.

[Hardwood]

My wife and I are in our 3rd house, and I now have the best shop I ever had. The key (as you are doing) was to develop a good plan before I started. I am fortunate to have a 800 square foot basement shop with 9 foot ceilings (and a wife who doesn't pay attention to my woodshop budget. In turn, I ignore her photography budget). 

Before I put any tools in, my brother-in-law (electrician) and I installed plenty of electrical outlets. I then painted all of the walls white and installed probably 20 fluorescent lights with daylight LED bulbs. 

I then decided where to locate my table saw and work bench, and then other tools and work areas followed those two. For example, once I knew where the table saw was going, it was pretty easy to decide where to put my dust collection. And once I knew where my work bench was going, I knew where I was going to put my hand tools etc.