I reckon I'd be pretty generous and give at least half of it away between friends, family and charities. Then go nuts with the rest. Or at least nuts by my fairly modest standards.
Build a house that's bigger than it needs to be. Include all those rooms I always wanted but never had, games room, comic room/library, office, bar, sex dungeon, steam room etc. Make sure it's zombie proof (the Missus will insist).
Probably buy a black Ford Capri and get a massive Punisher Skull on the bonnet. Also a second car with more than two seats.
Buy Garth Ennis' Punisher Omnibus.
Get a gazillion tattoos.
Buy a dog. Pharaoh Hound? Belgian Malinois? Dalmatian? I dunno.
Get a box a Man City.
That would all make me pretty happy.