I really only carry one bag at a time; I can't get into a bag 'wardrobe' and changing them over for different outfits etc.
This is my everyday bag, a Kitamura. My bags have to be very functional - they have to hold my stainless steel coffee mug, my wallet, the Blackberry and my current knittng project. Occasionally I have to carry 81/2 by 11 inch drawings or files for work so I need a fairly large bag to be a briefcase too.
this is my black bag for winter, by Morris B, a Canadian company. It's similar to the tan bag - large enough for all the things I need to carry day to day, long enough strap that it goes over my shoulder, made from real leather.