You don't want a bike that is too small or large and hence un-comfortable but, that doesn't mean you don't have options... As i figure it, you want a bicycle with a slackish seat-angle(good rear-ward balance) and a mid-ranged head angle(less flop at low speed)... If you look at the geometry of "snow bikes" like surley's pugsley and other frames out there you can get a good idea of what they're trying to go for. Often this type of frame turns out to be a mountain bike.
If you're worried about ice, get some studded tires... no matter the type of bicycle there is a good chance ice will catch you off-guard so get some studs!
Bottom bracket height is something you can look at, too low and your feet drag on snow, too high and your feet point up to the sky
