We rented points this year due to buying a resale and having a LOT of points to use in a couple of months time. We also took advantage of them and took an extra trip ourselves-it was just too many points to use so quickly.
Even though we have a fair amount of points, somehow we still seem to use them....we would rent if we found ourselves unable to use them for some reason but it definately is not something that I think will happen often!