With all that money.... you can help a lot of people. I hardly see how one would even see themselves spending more than 12 million dollars or so (unless they're saving money for their descendents, bahaha). I dunno. I'd probably keep 50 million or so to myself, and give the rest to charity, family, friends, bla bla bla.
I'd buy a lot of forums, domains, etc. I'd buy a ton of sports memorabilia. I'd save money for college, and then I would of course donate part of the money to charity.
I would just purchase video games (Including buying premium money ^_^) and other pieces of technology, food, furniture, valuables, etc. which is one of the main things I'd have one quadrillion dollars.
I'd still have about 90,000 (or maybe even more) or 60,000 left though. Then I'd just leave it to shopping whenever I need something. 😉
Realistically thinking, I'm thinking that it'd actually be... difficult to spend a quadrillion dollars. That's the equivalent of spending a billion dollars... a million times.