I never see any good mileage runs from Phoenix but did happen upon this one. You can fly on UA in actual economy for $100 RT from PHX-ORD-RDU-IAH-PHX for a total of 4139 PQM. This equates to 2.4CPM. You can also fly Saturday, Sunday, or Monday through Tuesday to make it a long weekend trip. Hope someone gets some use out of it.
EDIT: Can also be done 9-10 JUL or a same-day on 25JUL. There may be significantly more availability.