I do a 19 mile round trip from the west side of Waltham to Harvard Square. Last winter I think I was off the bike for three days because of snowstorms.
Some thoughts:
I love studded tires - I use Schwalbe Marathon Winters; they are great for those frozen bits that are around every morning and for those days where the whole city is a skating rink. They suck in deep snow. Anything more than about 4 inches of heavy wet snow and they are unrideable.
No bike paths in the winter. While the DCR plows some of the bike paths, they do a really crappy job. Mostly I'm on plowed roads, and I don't find the narrowed lanes a problem. In lots of places you actually get more room in winter because two lanes become a lane and a half; that's a lane for cars and a half lane for me!
The bike is a mess of salt and slush pretty much every day. I give at a quick rinse with a 2 gallon garden sprayer full of soap and water. I just leave the sprayer in the garage - it never seems to freeze.