Priceline is great! I searched for a reasonable hotel around the BWI (Baltimore/Washington) area and I couldn't find anything for under $140 night (park/fly). I've used priceline several times in the past and have had great success. I bid $50 my first time and got the Courtyard by Marriott. I still have to pay for parking, but that will only cost about $40 at hotel, so for a total of $90, I feel I still have a great deal.
I have also used them for our trips to Washington and will use them for our trip to Niagara this summer. Good luck!