A Carradice Barley is the perfect commuter bag for me in the cooler months, but I get by with a smaller Acorn bag when it's warm and I have less gear to carry. I currently have no need for racks and panniers as I try to travel light. I keep food and spare clothes, shoes in my office and restock on days that I drive, so that minimizes the amount I need to carry most days. My commute route is pretty hilly and I don't want to lug racks and panniers up and down all the hills.