We took the 10 free nights, when we bought our 280 points.
I really spent some time on the "free stay" paper work. The paper work indicates that rooms are limited, but they are only limited by the number of "standard view/type" rooms at the individual resorts (everything except GF and All Stars). Each is booked on a first come, first served bassis, no earlier than 7 months prior, or as late as one week prior.
All stays must be booked by June 1st, 2003, with all stays completed by July 1st, 2003. You can cancel a "free" reservation, and rebook it at a later date. They prefer at least a 5 day prior notice for cancelations, but there seems to be away around that.