Thumb Score: +1

Frontier Airlines [flyfrontier.com]
Book by: June 5
Travel by June 22
Promo code: SAVE50

Markets excluded from this offer include:

Denver, CO to/from Pittsburgh, PA
Denver, CO to/from Knoxville, TN
Denver, CO to/from Philadelphia, PA
Los Angeles, CA to/from Orlando, FL
Charlotte, NC to/from Denver, CO
Nashville, TN to/from Denver, CO
Denver, CO to/from Washington, D.C. (Dulles)
Denver, CO to/from Raleigh, NC
Denver, CO to/from Orlando, FL