I've seen stories in the past of big winners "staying as they are", e.g. still driving their old bomb, etc.
Bugger that

Assuming a BIG win (i.e. money no object) I'd retire immediately, get myself a Bugatti Veyron (for Sundays) and a selection of others for the weekdays, a massive mansion on the beachfront (here in Melb would be fine) obviously with an observatory, and an iMax home theatre

; and a few other properties in dark sky locations with a piloted heli to take me there, permanent box at all major tennis events (well, it's topical) and my own jet to get me there. Basically lash out to the max, having enough left over to invest and see me out!
Yeah I'd also try and think of a way of helping out family members without it causing problems, as that would be a tough task methinks.
Probably pick a charity or two as well
Except, I don't buy lotto tickets.