First off, I'd pay my parents back, plus interest, for the chunk of my top surgery they funded, as well as the loans they took out to send me to school.
I'd buy a nice little condo in Chicago, near the lakefront. Probably on the north side, but not too far north.
I'd be able to pay my own way through college without going into debt.
I'd pay my grandfather back for buying me and my sister a car. I'd ensure my sister had a car of her own, and probably buy my parents new cars since they don't like their current ones very much.
I've lost track of how much I've spent, but those are the big things. The little things are actually what comes to mind first. I could buy lots of art and craft supplies, finish fixing up my bike, dress myself more the way I wanted, build up my rock and mineral collection. I'm pretty easy to please.