Honestly, a lot of these decisions have little to do with the weather forecast and mostly do with whether the busses will start and the parking lots will be cleared. School systems here in the Northeast are taking more days than normal - yeah, we're getting pummeled but many of the problems are stemming from not having any where to put the darn snow right now.[/QUOTE]
I am in MA and I agree with the bolded part. We have snow banks that are impossible to see around and 2 lane roads down to 1 1/2 lanes. It is snowing right now and we are supposed to get another 6-12 inches of snow.
My daughters have had 3 now days in 25 days. One has also had a couple of 2 hour delays. The elementary schools have children who walk to school so the decision to cancel is based not only on the road conditions but on walking conditions. Plus we are a coastal community and some bus routes can be inpassable due to flooding.
I don't blame the school systems when they are open or closed, it is a tough call to make and someone will always be mad.
. Away from the metro area where there is more farmland and open spaces, they get a few snowdays or at least a few late starts each year because the rural roads drift so badly. If the 20"+ snowfall we had in December fell on a weekday, most of the metro would have had a snow day with that though-dang weekend snowstorms 
The professors occasionally would call of class because their cars were frozen shut, but never did the school call an official snow day. Oh, and this was in Michigan, right on the lake. We'd get dumped on literally every night.. don't miss it!