Thanks for the replies, fellas.
The 4 car garage is 45'10" by 23'4". Large enough for storing 4 cars, since the average 2 car garage is about 21-22' deep. I'm not planning on servicing the cars here, so keeping the size down is necessary to stay under budget and residential size constraints.
I don't own any SUV's, so I think that the length is OK. The 2 car garage is 35' wide and 22'4" deep. The extra width will be used for a workspace, cabinets, etc.
Other news:
After discussing floor painting with the concrete subcontractor, I decided that epoxy paint is not the way to go. Even with professional preparation, most epoxy finishes are destined to fail due to ground moisture issues.
I'm going with full thickness concrete staining, with possible acid etching and satin finish clear coat.
Stain Crete garage floors
The ceiling in the 4 car garage will be 11' high, so that I can fit my "dream lift" from
www.revolutionlifts.com
And so, that's where I am now. Details as the house/garage unfolds...
Dean