With the addition of CO codeshares, there are some really interesting UA routings to NYC now.
I'm seeing SFO-EWR-DCA-LGA
-ORD-LAX-SFO in Feb on ITA for $287. Should be at least 6500 miles (for those that get 500 for the short segments), and naturally, for ~$30 less than the direct versions
Certainly not MR, but great for people who actually need to fly this route. Can't get it to backtrack on the reverse, but should be possible.