Unless I'm desperate for the SPG stay credit or are travelling with work, I almost always go for Priceline these days. Generally end up with a decent hotel (the Marriott and the Skyline seem to come up most frequently it seems to me), though no points of course and no real favours in the room department. I'm always up at some ungodly early hour and arrive pretty late so having an ultra-nice upgraded room would normally be lost on me in this case...