Update!; visit http://www.vintageadbrowser.com/got-milk-ads and look at this vintage "got milk?" ads. If there's a picture on the cover, I don't think it should look like a perplexed or confused person, but rather someone successful and confident--yes, they have all that, but have they "got god?" I realize the title and author name will have to be much larger than in the original ads, and we certainly don't want a photo of someone as old as Joan Rivers (no offense to her intended ;-) ) but it should be an image of someone cool, popular, attractive, who seems to have their act together.
I hope these latest thoughts are helpful.
Design Update 2:
I've launched a poll, and though the reactions to various covers are predictably mixed, here's one thing I've figured out--the adults won't pick up a book with teens on it, and vice versa. And there's some pretty heavy stuff in here, though it's simply explained, and I'm thinking maybe some adults would want to read it.
So instead of photos of kids/teens, maybe the image should be of a professor type, maybe a guy in a cap and gown looking out at the reader? Maybe even some kind of humorous expression, like he's asking the question, "Got God?"
I apologize for sounding like I'm changing my mind, but I'm learning things from the poll and I want this to be the best it can be. Thank you!
(I've even helped by uploading some istockphoto shots that I think would work!)