I take it they don't use salt in the DC area. Here in the snow belt we get plenty of freeze thaw cycles and very few days with dry snow but salt on the roads means there is very seldom ice on the roads. The roads are usually only slick due to snow. I find studs very useful in those conditions but very slow otherwise. I perfer having two bikes for winter but both bikes would become covered in salt and road grime so I make due with one. I tend to put on my studded tires when they predict several snows in a week and take them off when clear conditions or lights snows are predicted. I find studs are only necessary when the snow accumlates more than an inch or two on the roads. I use a 700x35C tire with minimal tread. Given the efficiency of our road crews this only happens when the snow fall totals 6 or more inches in a short time. Obviously your conditions may vary but it is quite possible you will not need studded tires in the winter.
Craig