Per-person sq. ft. of home interior seems like a far better metric...but you analyze the data you have, not the data you wish you had.<p>I still recall a 1990's newspaper article about the largest piano store in (trendy, upscale) Ann Arbor, Michigan. Supposedly, their #1 driver of sales was new homeowners whose McMansions had huge, empty great rooms. It didn't matter if they couldn't play the piano, and had no kids - a grand piano filled up a lot of space, and looked suitably upscale.