I'm a fan of the Novara Headwind pants. The block the wind on the front but are breathable on the back. That with some kind of a coat with a wool baselayer should be fine for DC. A wool beanie under the helmet also makes a huge difference. The hard item I find is gloves. I tend to use cheap wool gloves over a windproof liner. I keep a second pair in the office in case they get wet coming in.