As for the two guys, well...how does statutory rape play in for the 17 year old? Not sure I get that. I am also of a mind to give them light sentences even for that because...well...boys will be boys and if she was a willing participant, you know? That's a tough call, too.
But my rational side says if we take these girls who might be horrible examples of kids gone totally down the sadistic path of bullying and teasing, did they actually do anything that would have gotten them in trouble if a disturbed young lady hadn't committed suicide? Are we really able to hold them accountable for the kind of senseless death that, by default, lays the suspicion at the hands of the one who did the killing: the one who committed suicide?
If someone needs to be blamed, blame the parents who weren't listening, the teachers who didn't intervene, the system that allows it...whatever. But don't take these kids who acted like kids and turn them into the animals that products of the justice system usually are.