The WSJ had an article on fuel burn:
http://online.wsj.com/article/SB1000...677748380.html
Some stats were: Boeing says the champ in its current line-up is the 737-900 with 180 passengers flying 1,000 miles. It gets nearly 99 mpg. Boeing says its 777-200ER wide-body jet gets nearly 82 miles to the gallon with 301 seats, all full, on a 3,000-mile trip. But increase the flight to 6,000 miles, and the same plane only gets 76 mpg per seat. The Airbus A380 super-jumbo, the largest passenger airplane in the world with more than 500 seats, averages about 65 miles per gallon per seat, The A320, a single-aisle plane with about 150 seats, averages roughly 77 seat miles to the gallon, according to the manufacturer