My close friend is a professional long armer, and her living room is now her quilting studio. She and hubby and daughter only use the family room, and she ran out of room in the small bedroom she was using for her sewing room. That room is now her fabric storage and cutting room, and her domestic machine is also in there.
Another guild member I know uses her dining room for her long arm studio. They have an open floor plan, and she has a large eat-in kitchen, so didn't need two dining tables.