I have my LA in the DR. It's just hubby & me and we always eat in the kitchen so....it went in the DR. The room is small, 9' x 12' so the machine sits in the very middle of the room. I can do up to 115" quilts (works for me), store the rolls of batting under the machine and have a metal book case for other items. My thread rack is on the wall and have a rack that hangs over the back of the door to put folded quilts on. Your garage would work just fine if you insulate the walls and put something in the floor to help hold in the heat in winter and small air cond. for the summer.
You could also use a fold up couch in you spare BD for guests as 14' x 14' foot work be snug, but would work. Hmmm....like quiltyfeelings said....is a kitchen essential. LOL