This year I made a trip down to my local Military Surplus store and bought some wool pants that came from the Swedish Army. They are light brown and I think quite stylish with their button down pockets. I am all legs--these are just long enough to tuck into my Sorel packs. I got the waist big enough to fit over my regular pants but I wear either a pair of tights or polypro long underwear underneath so there is plenty of room to move.
My riding was severely curtailed in December but the few times I've used them in single digit weather I was toasty warm.
Very affordable, too--my pair was $29.
Jeff