I would build 2'x2' cubes and screw together so I end up with 4'x2' sections of cabinets. Then build doors for the fronts. I'd wrap my garage with them. Mount tops low enough so that you can squeeze tubs, etc on top of the cabinets as well.
Depending on thickness of rigid foam, I would cut to fit and insulate my garage doors. Also, I would insulate above garage as NUTTSGT mentioned.
And I'd probably have way more work bench, shelving and pull out drawers than I need. Remember when doing work bench tops to stack (2) pieces of 3/4" plywood (stagger joints) and then top with a 1/4" hardboard to hide all the seams. Something like below....