You could probably get by without snow tires on the G35, although the Blizzaks are exceptional. The Bridgestone Potenza RE960AS Pole Position is a high performance all-season tire. It's pricey, but not really much more than the Blizzaks. According to the reviews on Tirerack.com, it scores "excellent" in winter and wet driving conditions. Bridgestone pretty much wipes the floor with Goodyears in every category you can think of.
Bridgestone Potenza RE960AS Pole Position 
