I can give you the name of the guy who designed our garage, the engineer, and the contractor who framed it. Our wasn't as big, 2000 SF, but it was a good place to practice on before building the house.

A garage that big, add a 3/4 bath (nothing fancy), office, a mixture of 110v and 220v outlets EVERYWHERE, lots of lights. Insulation helps keep our shop cool in the summer and much warmer in the winter. We went with a flat wall finish and we painted it. I wish I had put more exterior lights outside. Don't forget to wire switched outlets for Xmas lights.

Have fun!