I designed my 3 bay garage myself, and it has worked well under a variety of projects and jobs. Versatility is a good thing to try and design before building. I did 2 things that I would have changed: I had a very small bathroom for the toilet but 10' ceilings: it reminds me of a vertical coffin. The second thing I would change is to give more room on the sides for workbenches relative to the garage doors/cars.
Now then, things that I did right: lots of light: 18 8 foot double lamp fluorescent light fixtures on 3 primary circuits. One can never have enough light. Plan on epoxy painting the floor but go light on the sand additive. Along the workbench area, I installed two electrical outlet strips, one at about 4 foot height, the other about 2 foot. One never has enough electrical outlets nearby. Internet access was planned with underground lines (this was long before wireless). Depending upon where you are, central AC/heat should be strongly considered; insulation of the walls and ceilings should also be considered. No need to be uncomfortable in your work area. Deep work sink with running water. If you can, have small enclosed rooms where you can store parts that can be easily damaged out of the way.
Some folks really like pegboard; I find it takes too much wall space and it is hard to keep the pegs in the board. Tools belong in tool boxes, not on the wall, IMHO.