Advertising: why I'm going with cost-per-impression rather than cost-per-click … but am I being stupid?

I’ve got two online ad campaigns running. One is based on cost-per-clicks (how many times someone clicks on it and goes to my site) the other is a cost-per-impression (how many times it appears on computer screens across the US). Both are targeted to specific demographics.  The cost-per-click ad is getting a higher click-rate-per-impression than […]