Well part of the deal with the wife was that I wanted somewhere decent to work on the car, sure we have a 3 car garage but this would be car No 4 and I wanted heat and space. We don't have acres of property so a separate building wasn't really on so our only option was to extend out of the back of the garage.
I wanted as much space as possible without being on top of the deck or in the water runoff area, also wanted an elevated ceiling so that I could get a lift in there too. Had an architect draw up some plans, the main reason being I wanted it to look like part of the house rather than some lean too.
Gas inlet was real close so plumbing in a heater wasn't too much grief and I had them put a separate fuse panel in the addition to be sure I had enough juice including the 220V for the lift. I also put in cable for the TV and hook up for a phone, whole thing is insulated so should be comfortable during those long winter evenings.
Here are some photos of the construction.