If you do one of the "travel rewards" you can get a much better rate - 1 to 1.

It does come with a 7 day Marriott certificate, that is good for a year, and can be extended another year.

Link:

http://www.marriott.com/rewards/usepoints/morepack.mi

FYI: US Airways is giving a 50% bonus on miles transferred this way, so that might be a better way to go, since they are both * Alliance.