I am using a 15 year old Peugeot MB I picked up for $50 for commuting. Replaced the knobby tires with 1.5" slicks. I got it just before the winter started so I had a long time to go over everything. New bearings and grease everywhere except for the pedals. A steel frame with no suspension. I never thought a bicycle needs a suspension because that is what your legs are for. New cables and new indexed shifters. The old Peugeot feels like a new bike. I will replace the pedals with a set of clipless Shimano's when I am a bit more confident riding it through the traffic.
I have a almost brand new condition 1978 Raleigh Competition GS which is a bit to dainty for the commute. The streets are full of gravel from the winter and the city hasn't started fixing all the pot holes. Perhaps later in the summer I will commute on the Raleigh. I can park my bicycle in my office. When winter comes back, I will see if I am tough enough to do it. This morning, it was -2 C and that wasn't a problem.