Twice within the past year, I've managed to find a better rate for a Marriott property than was available on the website. Both were hotels on the West Coast...a full-serve Marriott and a Courtyard.

I didn't attempt to invoke the guarantee. I was just happy to get the better rate (and didn't want to create a "fuss"). Besides, the additional savings involved wasn't that extreme (but still pretty nice), and I still got my points.

I also have to say it didn't take much effort to beat what was showing on the Marriott website.