Charlie had VERY sensetive skin as a puppy and would get dry flaky skin if I wasn't careful, I use Cain & Able Pepermint and Tea Tree conditioning Shampoo on them both. I love that it has good natural oils in it and is a mild bug repelent.
http://www.healthypetboutique.com/servlet/the-343/CAIN-&-ABLE-SHAMPOO/Detail