Priceline--totally worth it--but you have to bid (don't be scared!).
Before you bid on Priceline (which is cheaper than Hotwire), go to betterbidding.com and see what others have bid for the same hotels (star ratings, amenities, etc.) in the same location.
I haven't paid full price in years.
Three and Four Star Hotels for Half or More off their Rated Prices! Promise!