I am due to travel to Des Moines, IA in a couple of weeks. I will be there for a couple of days (including Valentine's Day

). I am hoping to get some feedback from others in regards to cold weather dressing specific to my needs (in other words, I need more input than "layers").
I am a VERY warm blooded person (Susan says I am a human furnace). On my last trip to Des Moines in mid November, highs were in the 30's and lows in the teens. I did not have a problem with that: a leather jacket to get from building to car and vice-versa and the rest of the time I wore jeans and light-weight short-sleeved shirts. On the previous trip in early November, highs in the 40s and lows in the 20's and I never even wore my jacket. For these trips, I do not spend any time outdoors other than mentioned above.
I expect it to be colder this time and probably snowing. I was planning on getting some silk long underwear, thicker socks and some gloves. Since I am almost never outdoors, do I need anything more than this? I want to be prepared, but I don't want to go nuts. Also, I don't want to be roasting when I am indoors.
Suggestions/feedback?