That's true: there are complaints about S6 of Buffy, but I have always found it to be an excellent trauma framework, and an excellent way of looking at emotion and grief. I think S5 of Buffy also does some good work with the death of Buffy's mom. S02-03 is much less successful, and it's interesting to think about those in context of one another. Another show I remember dealing with grief well, at least some of the time, was Six Feet Under -- but I suppose it would want to, given the premise.