NW Montgomery county is a good spot if you want to be relatively close to DC and also be on the winning side of many marginal storms. Clarksburg and Gaithersburg are pretty good spots for that. Damascus is a great spot for snow, but it's about an hour away, so long commutes would be the tradeoff.
If you're looking at Virginia, then Reston, Sterling, or anywhere close to IAD would help. Even Tyson's Corner and Vienna do well in a lot of storms, though they are expensive and upscale.
Here's a clearer version of the map psuhoffman posted. It's pretty accurate for the most part (though it's a bit old and based on 1971-2000 averages), but I'd say that in many of the north/west spots, it might even be slightly underdone (Damascus for example probably averages 30).