Probably a couple cases of champagne.
After that, I'd buy my parents an annuity that left them more than comfortable forever and a new house.
For me, there are several places all over the world I've always wanted to go. I'd plan a huge trip and bring a long friends, family and I'd do a lot of giving. I'm pretty simple.
$300 mill at 6% is 18 mill or 1.5 mill per month, never touching the principl. $50k per day. Giving a broke family $10k changes their life. I'd find a lot of those families. Probably start in New York/New Jersey.