I'll tell you-- I'm a big fan. The difference in DL between now and just 5 years ago is huge. The biggest difference is the employees; they're no longer anywhere near as surly.

And you have to hand it to the guy-- he bought a whole frickin' oil refinery. Only time will tell on that one, but he thinks big.

The other really brilliant thing I think Delta did was that Amex Platinum MQM transfer bonus a few years ago; I generally would spread my travel around, and fly the lowest cost carrier-- but getting FO status was like a taste of crack, and as my travel patterns have increased dramatically, it's been an easy choice to stay with DL. (Doesn't hurt that I'm out of NYC, where a T fare to SFO is under $300 rt-- or that I'm 6 for 6 on upgrades since hitting PM.)