I ma working through my garage now. While i did not get to build it, I did design one and am incorporating my ideas. Some thoughts:
1. Floor drains. PUT THEM IN.
2. What is your plan for heat? A Mr. Heater 75,000 BTU will heat that garage without trying hard. I have a Hot Dawg heater in the new garage and it is too loud.
3. Put in some ceiling fans. Even one will help move air, reduce heat costs and cool in the summer.
4. Pull a network cable into the building. Pull a coax cable as well.
5. Run airlines inside the walls before the sheet rock or peg board.
6. Sheet Rock or Peg Board, insulate first. I did NOT do that on my last one and it was a mistake.
7. Sink is a must. I just have the tub sink with hot & cold water with a hose connection as well. (softened so I can wash the cars

)
8. While you are plumbing.... I just bought a urinal I intend to instal (my wife is NOT happy).
9. What is your plan for the floors? Lots of options.
Keep the pictures coming!