I am not in the habit of leaving the house without atleast 1 camera, frequently 2 cameras.
I have a naneu pro lima (messenger style) bag that I used a ton until recently, awesome smaller bag, holds a nikon f3+50mm+ motor drive and 10 rolls of film fine.
Recently I've taken to using a dedicated flash for the F3, SB-12, which doesn't really fit in the bag assembled, but works fine with the flash off.
I also picked up a SB-11 handle mount monster flash that lives on my Mamiya RB67, the combo barely fits assembled in a bare messenger bag I got at old navy a few years ago, theres really not a good bag for such a big camera. I used to keep it in an insulated fishing bag. It had loops for fishing lures in the front pocket that were perfect for rolls of 120 and the side pockets are just the right size for extra backs and a meter.
I've had my naneu bag for almost 2 years now and the strap lost a couple stitches, other than that it's as-new. I'm really hard on my equipment(hence the F3), and I'm amazed at how this bag has held up to daily abuse, countless airports, boats, bikes, being tossed, dragged, my dog, seawater, sand and rain. I wouldn't hesitate to buy another from the same brand and I'm hoping for the larger Tango for christmas.