I really thought about breaking this into two posts but this was just simpler. This is not a bad deal at all for a HUB run that is one you do not have to position to take. Normally I like to, under SkyMiles 2015, to have a run at about 4CPM for a weekday but for a hub captive to do this all in one day from home works! You decide.
You can work this from CVG or DTW with the lowest cost and highest yields I could find were connecting both ways via MSP from CVG but there are many more days open if you connect via LGA both ways. August seems to have the most open dates from CVG with limited dates from DTW. Anyway, here is open option:
3,364 MQMs at 5.3CPM
Bookable on Delta.com
Be sure to use switch DL+ X:MSP or X:LGA if you are searching via ITA Matrix for other months. Another idea, just for grins and max savings, is using FLEX PERKS points and booking two days back with multi-leg search and be sure to keep the total UNDER $400 with just 20,000 points and you get to fly two days in a row for just one free (or almost free) Flex Perks ticket 🙂