I'm amazed at people who live in Nashville and do between 130-140 flights a year. But to each his own.
Work flying plus leasure travel usually is sufficient to get me to top tier. If I were 10K miles short, would I MR? You bet. Upgrades, both domestic and international for a year would get me on a plane just to maintain status. I also like burning miles at the end of the year once I have requalified for travel. If you are going to travel ORD-HKG, F is much nicer than J. Trust me on this. Free is also better than $$$.
I have only MR'd once. I had a ticket with value expiring, and I had the opportunity to convert the value into 80K miles by yoyo-ing to the west coat for a weekend. Did it simply to have more miles in my account for trans-pac or tran-atl travel later on. I sat in F and read books and relaxed on the MR. And got to try In-N-Out burger outside LAX.