The best way I've seen designed is using a Simpson MPBZ Moment Post Base embedded in the concrete footing, with the 4x4 or 6x6 post on top of it. I think it's pretty new, and Simpson isn't pushing them on us, so people haven't seen them around much.
It's great because none of the wood post is below the ground, so you won't have the potential problems you're trying to prevent. It's the only post base they have that doesn't require the top of the post to be supported.
This post base even has a built-in 1" standoff to keep the wood post away from direct water and concrete contact.
