Given the current interest in finding the lowest rate at a Marriott I suggest that the website include a slider, much like on Sidestep and Jayak, that allows you to select a price or to see the entire price range for any Marriott search. As you move the slider to higher prices the hotels would of course become more available, and as you go toward the lower lever they would diminish.
I would put all the hotel rates, regardless of type of rate and restrictions, on the slider, from the lowest (Friends and Family) to the highest (Full Rate).
Marriott might also consider having a "Flexible Date" slider that would allow the traveler to look at alternative dates for better rates. Jet Blue and others do this on their sites.