As much as is possible but not out of personal greed.
My multi millions would go to -
Cancer research
Heart disease
Salvation army
Shelter
R.S.P.C.A
Rescued greyhounds
The lottery: a tax on disappointment, I call it hehe...
I would like as much as possible but (genuinely) try to do some long term good with it. My parents always say a few grand would do... well, why not win big and then give it away if that's all you want!