I've already registered to donate body parts, and after that give the rest to medical science if they can use it.
Mrs O. prefers the route of being cremated and having the ashes put into a sapling's root-ball for planting.
My 'instructions' in the event she's not around, for my kids are 'do whatever's cheapest' and remember what I was and don't fear for me now that I'm not.
O.