I concur with all of the above---------we have three car garage, under the house-------three doors, plus small access door...........I would not go with a large-2-car door if I were to do it over again. 

I should have made the house 4-6 feet wider, just to get the additional width in the garages.........we have to park the vehicles too close to the walls for my tastes, just to have enough room to open driver's side doors.

Floor drains---------absolute necessity.........

......we tied our garage drains into the tile on the house footings.........not sure that was the most brilliant thing to have done------seemed to be the best at the time of construction when sticker shock had set in, but  now with all the rain we have had in IA, we're getting some backflow from the footings tile into the garages................and that ain't keeping Momma happy!

We put in oversized garage door openers..........merely a few dollars more to get the bigger hp--------that was a win.

Put in lots of lights.................when the cars are in there, a lot of light is blocked.

Since ours are under the house, we have never had freezing problems, unless snow cakes under the garage doors and I get too lazy to shovel it out, and the wind blows under the doors.

I assume it is standard for anyone who understands cement, but our cement guy did a slight "lip" at the garage door opening, so water would not run towards the house..........a little thing, but quite valuable I have noticed over the years.

I made sure we had good flat areas on the walls in front of the vehicles so I could put mirrors on those walls, so driver can see that the garage doors are all the way in up position before trying to back out----------I use mine daily------

------I have never seen the Blonde use hers, regardless of the amount of my whining..............

............(like my dad told me one time when I commented that I thought Mom spent too much money on groceries-----I worked at the grocery store at the time and of course was an expert on getting the most for a buck-----------his comment----"it's just easier to work a few more hours than it is to put up with the verbage")------

----so I merely have a small reserve fund set aside to cover the damage to the rear of the car plus a new garage door...............when it happens..........