for commuing i'd get an old steelie form the 80s, fix it up a bit, add a rack, basket fenders, slap some slick 28 or 32c tires and lights and you will have a year round bike thats only 30-35lbs. the point of a commuter is that it can get stolen or crashed and its not a big deal. if you got money to burn then check out a surly crosscheck or anything from salsa. if you have rought roads or snow then go mtb with front disc brake.
keep the carbon fiber bike for group rides and weekend warrior type stuff