The trick is to use the "multi-city" option on the booking engine. Use nwa.com so you get 2000 miles for your first trip and 500 after that. Pay with a Visa (before 12/31 I think) and get another 1000 miles.

You forgot DTW as a hub too.

What you do is put in cities besides the hub. For example, if I want to go to SAT and grab good miles, for my segments I put in PHX-EWR, EWR-SAT, SAT-CMH, and CMH-PHX. This forces the engine to route me through hubs, since that's how the hub and spoke system works. The actual trip generated by these pairs was PHX-MSP, MSP-EWR, EWR-MEM, MEM-SAT, SAT-MEM, MEM-CMH, CMH-DTW,& DTW-PHX.

Do a search for "mileage run primer" and read what tvl4free posted, it's enlightening.

Good luck.