Alex,
IMO, display ad campaigns are branding campaigns. The concept is to put your name out there and fight with all the other ads in the hope that your name sticks with a few of them (a classical broadcast marketing model). The CTR is pathetic because of banner blindness and lack of context (i.e. I'm on ESPN to see the NFL draft results, not look for a car).
But, there is an attribution stat that may interest you, it's called "viewed thru conversions". The idea is simple. "how many visitors to my site, saw my banner ads?". This is additional visibility into the "branding message reaching shoppers".
In my old position at usedcarking.com, I got my PPC & SEO campaigns running on all cylinders, then, I went upstream to work the display ad universe.
HTH
Joe
p.s. look for "view thru data" to be avail around June/July. Reach out to me anytime.
p.p.s. The industry calls it "viewed thru conversions", IMO, it should be called "viewed thru visits" and from that group you get "viewed thru conversions".
