If you're going to be footing the airfare bill (leisure travel) and don't mind riding in coach open seating, you should consider Southwest. They fly non-stop to many cities in the eastern US (though some to "alternate" airports) for sale prices of $34 each way plus tax (usually around $88 total).

After 5.3 such paid trips in 12 months, you get a roundtrip award ticket (can also be used as two one-way award tickets) with just a handful of blackout dates and no other capacity controls.

And as they are the dominant carrier at BWI, there are a lot of flight options (even some non-stops to the west coast).

But be warned: Boston is Providence, New York is Long Island, and there's no service to Atlanta, Denver, or Minneapolis.