This is actually an interesting piece of question. While a lot of people are going to say that they'll invest most of the cash, they tend to forget how hard it is to actually do that. You'd realize that you need more than just having the money to actually invest, you also need the discipline to do it. Trust me, a lot of bills will prop their heads up and you'll want to satisfy them all, not to mention the fantasies you've always dreamt about.
Personally, I'd say the best thing to do is to actually invest about 70% of it so as to something to bank on later