The average U.S. hotel rate paid by American Express Business Travel clients during the first quarter increased 3 percent year over year to $150 per night

. San Francisco-based hotels saw the largest average rate increase among cities covered in the Amex report, up 16 percent from the first quarter 2010 to $206. Seattle hotel rates increased 9 percent, followed by Austin, Texas; Omaha, Neb.; and New York, all of which registered 8 percent increases. The average international room rate grew 4 percent to $238.