I'm in the same situation, but since I am in SE VA and we get snow perhaps 3-4 times a year in Jan/Feb, I'm leaning towards all seasons. Though I did drive with summer tires on all of last year and only got caught in the snow one time. Needless to say I don't want to do that again.
I'm looking at Michelin Pilot sport A/S and Continental extremecontact DWS 06 ultra high performance all seasons. I'd hate to lose the summer tire grip, but I can't compromise on safety.
I agree with those that say a dedicated set for folks that live in northern climates and see lots of snow and days with temps below freezing is the way to go.