I added on to my garage but the original size is 16x28 and it is separated by a wall and a step down on the floor so I see your dilemma.Some times I wish it was open but I use it as an extra separate work space.I agree with ROBJ it depends on your intentional use.If your doing body work by all means leave the wall up and use some car dollies to move the car over for room and work one side at a time.If its just storage for the most part leave the wall also.Only reason I see to take the wall out is for access to engine lifts,stands or other large objects that you don't want to drag around the outside.If you added the door for now and seen how you like it you can always take the wall down later but once you take it down its more work putting it back up if you decide you want it later.
