I'm feeling a little impassioned about this discussion I gotta say. I find it quite insulting that people should think that Dumbledore would allow Bill and his family to suffer because of... what.. some plan, that Dumbledore would think that he is SO necessary to the future that he has to drag everyone he loves through hell and that Dumbledore wouldn't be willing to sacrifice himself to save others/Harry.
Dumbledore's rants when he was taking the poison told us the depth of fear that Dumby felt at not being allowed to shoulder the pain for others, his desire to die so others can live, the idea that he would ... 'play' with them and that ideal , is ... so wrong!

If HP is about anything it's about struggle against bad, defending the good and the choices and sacrifices that are needed to do both. To deny Dumbledore his sacrifice is mean.

Dumbledore's death isn't about tricks or pain, it's a sacrifice for good, given in trust and in love.