I use the front bag/basket for stuff I need ready access to when getting on or off the bike. The lock, keys, wallet, phone, kleenex, etc. ride up there on the way to work. Once I'm at the office, my helmet and high-vis vest stay in there during the day. During the shoulder seasons, I might have an extra layer in there or gloves and so forth. The pannier on back is for stuff that I won't get into or out of during the ride or right at the beginning or end: laptop, change of clothes, lunch, etc.