One of the things I loved most about living in Boulder was the fact it was really designed as a multi-modal town. It is common to see the bike trails plowed before the streets! As long as you could get over the huge mound of snow along side the bike trails left by the plows, you are usually good to go. Stay on the trail as long as you can, as you have to get over the mound and fight through the slush of the streets to get to your destination. The other alternative is the bus! If you're just trying to get around the city, leave your car at home, as the city and regional bus network is pretty impressive. Just be sure to stand far back from the side of the road, as the cars and buses can spray slush and runoff on innocent bus stop bystanders.