Maybe this comment belongs in the FCM thread -- I've started regularly monitoring my trips and watching for the "upgrade to first" offer at a reasonable price. The opportunity to buy up has been showing up for me at $25 to $40 (depending on route/distance) per flight segment/leg this year. For me, the guaranteed FC seat, the 50% MQM bonus, and having to meet MQDs have made it worthwhile.
Sometimes it takes patience --
I booked a flight a few weeks ago and the upgrade offer was $919 on a $650 ticket. That I wasn't going to take.
Yesterday I changed the return to shorten my connection in DTW (got an earlier connection) and that cost $39 (no change fee surprisingly). A few minutes later the cost for the upgrade had dropped to $100 (4 legs).
Maybe I'm the kind of sucker DL is looking for, but if the $s per minute for the upgrade are low enough -- I'll pay for it.
Also in my experience so far this year, having a paid P/G/A ticket and being a diamond MM has made SDCs a breeze. I'm sure the diamond MM is important, but having the paid FC seems to be an big plus.