Put a good ammout on a bank account which was just spend-as-i-like
Put the vast majority into the highest pay-off safe investment i could find (or more likely, hire some very skiledl investor to find) and live off the interrest (which would be huge, given that 1 billion is a huge ammount of money)
Give however big shares to whoever i thought deserved it, be it fammily, friends or charity.
But yeah, mainly the huge secure investment, taht'd allow me, and in turn whoever inherrited the furtine after me to live off the interrest, never needing to withdraw money from the invested portion.