Chris-
The Ocean Course is public, but you will pay the premium rate for not staying at the resort (I'm assuming you're not).
TOC would certainly score some major brownie points with the father-in-law as it really is a fantastic course and place to play. Expensive sure, but worth it to me to at least see once, exp. if you are right in the area.
I can't speak for many other publics outside of Kiawah Island, but it seems the best place to be if golf is on the docket.
Have fun!