I think I would add 3 more rows of lighting, you just can't have enough lights in my opinion. You could also turn portions of your walls in to fold down work tables, especially if going with the plywood route. Although you would need to go 3/4 for the tables. These can come in very handy. I did this in my wood working shop and behind them was a mounted roll of paper to cover the work table. Someone mentioned an exhaust fan, these are nice when working with chemicals and its cold out. I would have a walk through door too, so your not always have to open the big garage doors. Personally I would have went with one big door vs two doors. It is just easier to work around a bigger door. Have some outlets high and some low, to late now but a couple in the middle of the floor are nice to have. But you could still put some in the ceiling. Having compressed air outlet is nice, but unless you are working with impact tools or woord working tools you likely dont need anything bigger than a pancake compressor. I have always found a wash basin to be useful, I drained mine outside but that depends on where you live. If you put cabinets on the walls leave ya about 10" from the ceiling to store long items. If you are going to have alot of valuable stuff in there you should think about security and insurance.
Not sure what all you have for equipment/tools but, like someone said wall space gets used up quickly, start trying to think of how you can double up things to use the space efficiently. When I had my wood working shop, I made all of my tools modular so they all mounted into one table/shelf system. Probably something you dont need but it worked great. Use standard sizes as much as possible, once you start getting into custom fitting things you will be chasing that for a long time (everytime you want to change/add something).