Also note, Marriott allows you to book award stays even when you don't have sufficient points in your account. As long as you have them before your stay (well approx. 1 week before your stay), you're good to go. Marriott will deduct the points from your account automatically when they generate the e-Certificate for the stay for the hotel which typically occurs approx. 1 week in advance. So to put it another way, if you see an award stay available you may be interested in for the future, book it immediately. You can always cancel later if it turns out you don't want it. Don't wait until you have the points in your account because it may no longer be available.

--Jon