It must be purchased by April 28 and a Saturday-night stay is required. Travel must take place Monday through Thursday and be completed by Sept. 6. This site is generally reliable, but sometimes it gets balky, especially if you ask it to search wide parameters. Click on the boxes that widen the search to all airports within 50 miles. Note that Travelocity has cut a deal with several airlines and will try to steer you to their fares.
Further review is necessary.
Hey, we never said this would be easy. Again, plug in DCA, IAD and BWI separately. We now know the cheapest fare is going to be out of BWI, but we're not sure whether Frontier or American is offering the best deal. Log on to a fourth site for a final check. Both sites are valuable in different ways.