Ethics: after Worf dies. When Crusher walks out, tears in her eyes, to tell Alexander and Troi.
Chain of Command II: "THERE ARE!!! ... FOUR LIGHTS!!!" And when Picard recounts to Troi that at one point, he thought he could see five lights. That got a tear in my eye.
This is one episode I tend to leave on the shelf, not because its bad, quite the opposite, its incredible television, but it is heavy going. Its like schindlers list or something, not really 'tuesday afternoon veiwing', if you catch my drift.
I dunno, just something about it, its a very powerful 2 parter.