My winter layers can vary quite a bit. As You've experienced before Ike, the weather in my neck of the woods can be quite variable, from warm and sunny to heavy, wet snow with a low ceiling. Lots of freeze/thaw cycles, so the ice creates a need for durability.
I have a "quiver" from which I choose pieces depending on expected conditions. My winter trips are usually shorter, 3-4 days, so I usually have very accurate forecasts at my disposal.
--Cap 2 Longsleeve
--Cap 4 Hoody
I usually wear these if conditions will be below 40F
--Fleece vest WS front/100 wt back
--100 wt fleece pullover
I wear one or both of these as layering pieces when on the move in conditions from 25F-0F. The vest in particular is nice as it is effective when layered both over or under my windshirt.
Always. Most used piece of gear.
--Shell. About to order a Montbell Torrent Flier, 9 oz. Paclite, pitzips. Hope the hood works for me.
I always carry a hardshell in winter; it's not uncommon to have rain and temps just above freezing in my locale.
--Montbell Mirage Parka
--Arcteryx Atom LT Hoody
Haven't used the Montbell yet, hopefully it and the Atom in conjunction will provide me with lots of options.
--Cap 2 briefs
--Cap 2 tights
Much like the tops, these are pretty much always worn if it's below 40F.
If it's going to be really cold, I'll use these instead of the Cap 2 tights.
--REI Sahara convertible pants
I wear these year round, they work well to cut wind, they're breathable and durable. I zip off the lower legs when it warms up, allowing my gaiters to keep my calves dry.
--Marmot Precip full-zip shell pants
Again, I always carry shells. These allow some venting and also make it easy when I'm wearing snowshoes or microspikes.
--Arcteryx Atom LT pants
I use these in camp and to supplement my sleeping bag, though the full-zips allow them to be used for layering. I've ner had conditions that cold, and don't want to!