Matt:
Boomer is right. I fly out of EWR and my favorite mileage run is EWR-IAH-SEA, about 6,600 Actual miles. When there is a sale between EWR and SEA, got to the CO site. You may have to go to the section that allows you to pick out the flights. Typically, the site will give you non-stops. By trying different combos, it will generally allow a routing through IAH. I believe that the rule is they will give you the fare on any routing that is less that 150% of the non-stop mileage. My favorite last year for about $280 was PHL-CLE-IAH-SEA-IAH-CLE-PHL.