What to do in the winter? Ride your bike.

Honestly, the only reason not to is if the snow is, as you said, "too deep". But what is too deep is only dependent on how well prepared you are- with my mountain bike I can do short rides in anything less than a foot, more than that and it's not worth the effort for me. But with a fatbike I could do much better- I saw one the other day at a used sporting goods store for only 150 bucks. Too bad I'm broke.