TEF, I was hoping someone would answer this as I often have the same question. This link you cited states the hotels listed are only a sampling of those offering Pointsavers rates. It'd be nice if Marriott kept an updated list that wasn't hidden behind multiple clicks of the mouse. Essentially, it sounds like to me that other than these samples, the only other way to find a pointsavers rate is to stumble onto it.
NUHUSKER: I agree. The only way to see if the hotel input has Pointsaver rates is to keep playing with the dates and (hopefully), as you say, one stumbles upon a pointsaver timeframe. It is confusing and hard to find what is available at a particular snapshot of time. But, until Marriott creates access to all available pointsaver availability, we are limited to 'stumbling across' those hotels offering pointsavers.
You are all correct that there is currently no source for viewing all PointSaver availability. Because hotels' PointSaver availability changes so frequently, it is difficult to maintain a comprehensive list at all times. However please note that the list available at http://www.marriott.com/rewards/marriottRewardsPointSavers.mi is updated weekly with the latest hotel information. As for searching all PointSaver availability, I wanted to let you know that this is being researched as a future capability on Marriott.com. Stay tuned! Regards, Laura