Air lines... I run air lines off the compressor along the walls! The you can have hook ups any where you want. That way you can get away with a shorter hose and it isnt all over the floor. Super cheap! I use copper pipe!
Anti Fatigue Mats ... Keep a couple that you can place near your project. They really reduce the pain in the back and legs if you are polishing or working standing up for any amount of time.
Central Vac ... If I could start from scratch, I would build in a central vac. Who likes to pull the shop vac around all of the time?! Similar advantages to the air compressor lines mentioned above.
I hope these are the kind of suggestions you were looking for!!:bigups
It would have to be floor and wall coverings. My current (also first) garage came with these coverings, and it helps make the garage cool on warm days, and more warm during colder days. It helps the atmosphere a lot IMO.