I agree.. one promotion I found good and made sense is the promotion from Northwest a year or so ago (not sure if it still exists). The promotion offer upgrades to 1st for connecting flights in full coach. I think it makes sense.

Airlines really do not need to do extra for us doing what we do. But promotions that offer double miles for new routes where we flew alternate airlines before and also connection bonuses (fly your airline and get a promotion for flying a connection vrs a direct on someone else). For example, United could offer bonus miles for connecting in Denver or SFO or Chicago for passengers originating elsewhere. This would increase revenue...

Makes sense!