I am based in a *A hub. The majority of my flights are on *A. In the past, I've had enough OW flights to make OWS as a secondary status. But it doesn't look as if I'll make it this time. Hence I'm looking in matches to OW.
Not too long ago, I completed the DL challenge. It was easy as pie, all it took was one eco return mainland Europe to LAX with transfers at East Coast or Midwest DL hubs in the lowest booking class.
If the impression I'm getting on the AAdvantage challenge is right, it's considerably harder than the DL challenge. And yeah, the spend requirement is the issue.