Instead of buying M fares, buy I fares on DL or Z fares on Air France. These a discounted business class tickets, they cost a few hundred dollars more than M class, but you don't need to burn miles on upgrades (or have to worry about clearing upgrades), and you get double MQM's (so fewer trips are needed to reach platinum -- you can hit 100K MQMs in as few as 4 RT's to Europe from the west coast.).

You need to buy your tickets 50 days in advance and stay at least 7 days in order to get this fare.