Well, I had my mind made up for me... I didn't realize IHG/PRC points could be converted into UA points. As easy as PRC points are to amass, and much easier for me to get than UA points, I'll be going back to IHG after I finish this Marriott challenge.

I won't be able to do a Staples/ink double dip, but air miles are where the bulk of my spending is and int'l flights are my weakest link on earnings.