This one is just TOPS for a weekend 1 day mileage run in 1st class. I mean you fly out and back same day all in 1st class. Get a 1 day GoGo pass and you are set for $8-16! It does work from Chicago to PHX just not as many open days till the end of the year. I am thinking about some November or December midweek days for myself maybe. Here are the numbers:
Cost $483 in 1st class
5,328 MQMs at 9.1CPM
Bookable on Delta.com
DM yields a ok 9,768 Skymiles per CWSI.net!
BTW if you are willing to do weekdays and out of MKE you can dive this down to 8CPM or lower.