Starwood.
No blackout dates ever. Very useful. Here's what I routinely do with my SP:
1. Book hotel rooms for free, especially useful since I have an odd work schedule, if I take a week off, I don't have to be back to work for 10 days. I commonly add a few nights on either end of a TS trip.
2. Book high-end hotels rooms using "Cash & Points," where you pay a small fee plus a reduced number of points. This can save SP when you are going somewhere swank. If you didn't mind spending the points, you could always get this room free as well.
3. Transfer points out to (almost any) airline FF program, getting a 5k point bonus for each 20k you transfer
4. Use SPG flights to buy a ticket. When you exercise this option, SPG just buys you a plane ticket and you earn FF miles on it. This is a great option if there is a killer fare sale on a long route, eg Hawaii.
The Starwood program is an awesome complement to TS ownership IMO. Sometimes I just need to add a few nights at my destination. Sometimes, however, my best TS deal occurs on a timeframe in which my FF tix are "overpriced." If I don't have enough miles in whatever program for 2 tix, I commonly obtain one "overpriced" FF ticket and the second free ticket using SP. That way I don't pull my hair our trying to balance TS availability and FF ticket availability.
H