Vulture's got some great oral histories this week. I just read the one about Buffy's 6th season Big Bad(s), and it explained so much the reasons season 6 is by far my favorite.
When I watched it for the first time, about a year ago, I had no idea where September 11, 2001 fell in the series. But it's so clear to me now why I love the arc of season 6 so much more than the others. That turn from light and fluffy to dark and human was so well-done.