I was looking for a bag to hold a body, 55210, 1855, microphone, battery, flash, etc. I looked at the bag mentioned already, the LowePro 140 and several others, bought 3 and the Crumpler 4 Million ended up being a perfect fit. The others were just a bit too small, too loose, not enough pockets, etc. I balked at the somewhat higher price but ended probably spending a day of time in stores looking, returning, etc. and in the end would have been way ahead to just buy the Crumpler when I first saw it.
I also have another bag that I keep all my legacy glass in, I find it easier for me to have 2 smaller bags than 1 large with everything, that way I have the basic "travel and snaps" bag and grab the second for more deliberate shots.