Going to 700c wheels will allow for fatter tires and/or studs or knobs which wil help with snow. However, usually the snow in Denver is gone fairly quickly so what I have are multiple wheels one pair of which have studs and one pair without. On those days when the roads are icy studs are very nice but a lot of drag when on dry pavement. In warmermonths you might have some gravel grinders and some road slicks as your set. One of the things I love about older bikes is their ability to run larger tires.