We are doing a reno on a 2001 home in N. GA (CZ 3A/4A).

I’m seeing a lot of conflicting info online about whether or not we should air seal and insulate the exterior walls of our unconditioned attached garage. There is not a living space directly above it, but there is attic space that is shared by the rest of the home. We already plan to air seal and insulate the garage ceiling and the wall that is shared by a living space (this wall also has our water heater closet in it). Is insulating all of an attached unconditioned garage a good idea in my climate zone? 

Our existing garage door is nowhere near air tight, so is air sealing all of the walls and insulating just futile anyway? I also worry about trapping hot humid air in there during our sometimes brutal summers. 

Thanks in advance for your input!
Tiffany