This site gives detailed analysis of all of the philosophical and moral dilemmas in every episode of both shows. It's really quite amazing what they've done. Some of the discussions are:
'Moral Ambiguities', 'Good and Evil', 'Philosophies Represented', etc.
Just for example, under 'WttH', we have: An entry on Vampire Slayers, Watchers, the Hellmouth, Psychic Dreams, Darla, Buffy's Moral and Ethical quandaries of taking on the 'mantle' of her Slayerhood or leaving it behind and her 'seize the day' philosophy.
I whole-heartedly recommend reading it. There are several ways of searching out information about the views represented in the series, though I always just like going episode by episode.