While I agree availability is very limited at timeshares, be very persistent and you can still find some. This year we're staying at Kauai Lagoons (2 Bedroom) in a couple of weeks as a rewards stay. Kauai Beach Club and Ko'olina Beach Club were also available the same week. In previous years I have had reward stays at Manor Club - Sequel, Maui Ocean Club, and Marriott Monarch (3 units the same week). The year I stayed at The Monarch, Barony Beach Club and Grande Ocean also had some availability.

To find the availability you need to check often and when something shows up, book it immediately. You can always cancel later if you decide not to go. I frequently will book a couple of different options for the same week well in advance and then cancel the one(s) I am not going to use 1 to 2 months out. YMMV....

--Jon