I went to a couple sites to find some perspective into average home size in the United States to possibly shed some light on the concerns regarding Al Gore's electrical bill.
Google Answers responded to a question about average home size in 2002. The average U.S. home size in 2001 was 2,300 square feet. I realize this is five years ago, but it takes some time for the majority of the country to upgrade the size of their homes, so I would suspect the 2006 number to still be below 3,000. Google Answers also listed their sources for determining the answer.