Try to "containerize" things. Then instead of say 15 items going into your bag, maybe you have now only 4 containers. Then try to find ways to keep those containers packed.

Like have a single lunch bag, box or whatever. Then prepare the lunch the night before and put the container in the fridge. In the morning, just pop the container in your lumbar/backpack/pannier/messengar bag.

For the clothes try these little folding things from Eagle Creek - they really work for me when I travel but I have the luxury of not having to carry clothes to work on my bike. I think you'll be able to fold your clothes the night before in one of those and pack it up all ready to go.

I have a set of keys for the office and the house that I ring clipped in my lumbar bag. They are dedicated to the bag which I commute with everyday.