Most wide open routes (using the term relatively) that I've seen so far are EWR-BUR and BDL-LAS. Everything else is incredibly spotty. DCA might prove really valuable due to the US promo if traveled before 9/30.
"In celebration of our new DCA service, earn double miles when you fly to or from Reagan National Airport.
Here’s how:
Book July 7 – August 5, 2012
Travel July 7 - September 30, 2012
No registration required" (Not double elite miles, just double award miles)