One thing I find frustrating about placement targeting campaigns (specifically image ads only) is that I never know what the minimum amount to get into the auction is for a given site. I have to raise my bid up, up some more, then more to find out where the entry point is.
You can bring it down from there after you're in the auction, but it's a pain.
AWA: Can you pass this feedback along? A "Minimum Suggested Bid" for a placement target (with images for instance) would be really helpful.