It's a funny thing ... I travel quite extensively for work yet I have very little involvement in the airline category. There are two reasons:  I have little choice in what airline I fly for work and  I've achieved the highest frequent flyer status on a certain airline and therefor am hard-pressed to fly anyone else. So I rarely pay attention to airline promotions, and even less so to airline advertising.
That said, a recent out-of-home Delta campaign running in New York has caught my eye. The tagline invites you to "Cheat on New York" [by traveling to other great cities]. I'm no critic, but the art direction and copy instantly resonated with me. I also get the sense that the campaign was developed based on deep insights from New Yorkers [and our sense of pride in the city].
I had a surprisingly tough time finding good screen shots. Here's a link to the promotional page on their website [and screen shot below], but it's not indicative of the creative. If anyone can provide a link I'm happy to post some images for those of you not in New York.