Buy enough for now (say for the next two or three years worth of trips) - there is a belief (which certainly has a large number of data points to support it) on this board that you'll get addonitis and have to add on later, but a few smaller contracts can be sold off individually - if you buy one large contract you'll be in an all or nothing situation if you have too many points. You can always buy more points later (though they probably will be more expensive) at VWL or at a different resort.