We just broke 40K points on our SPG account, and we want to use them for the 5/4 deal at the Swan. Has anyone done this already? We don't have airfare nailed down yet, but we think we have the dates; if I want to give myself a day's wiggle room, do they allow cancellations? Do the points get taken from the account when the ressie is made, or when you arrive? Anything else I should know?