It was kind of obvious that she was going to jump. I mean, Spike saying that it's always got to be blood, then Buffy saying twice that her and Dawn shared the same blood, and then the First Slayer saying that death was her gift.
Then she turned around, all slow and peaceful, and I could just tell that the orange in the sky was her path to heaven.
It's at that part where I start to cry!
I love the part where she runs in slow-motion towards the edge, and you hear her last words to Dawn as she closes the portal.
What really hits home is when her grave has been shown, and you get that one frame of silence before the theme tune.
I love that episode sooooooooooooooooo much!