1. Buy fancy yachts.
2. Continue running the business that made them rich.
3. Spend a token amount on a feel-good charity. The Foundation to Prevent Euthanasia of Cute Puppies or Whatever.
Gates has managed to convince them of another option:
4. Spend wealth to alleviate large causes of suffering that few/no groups are working on.
More than 3.3 million people who would have died of malaria are alive today.
I realize he can't take full responsibility for that, but considering all he's done, Bill Gates is a living saint.