Deadwood is excellent. Not suitable for children, though.
The reason I think it is good for kids to be exposed to profanity at home is that they are going to encounter it in the school hallways and playgrounds anyhow. Even 12-year-old kids talk like drunken sailors when they get away from adult supervision.
Now my wife and I never swear and not because we are prudes but because we both have mastered the English language and we are able to express ourselves with intelligent words. That said, hearing profanity from others does not offend us nor does it disturb us. It does usually cause us to render a lower opinion of that person's intelligence and education however.
I believe this attitude has rubbed off on our kids and they do not swear either - at least not in front of us. But we had no problem having them watch profanity-laden shows and movies with us from the time they were just little babies. As a result, they have grown up to be well-mannered, having learned what is and isn't appropriate language to use in public. I believe that the fact that they have become experts on profanity has helped them with their peers. They are not impressed (or shocked) to hear their peers utter profanity and they don't think it's very cool either.