New Camera Bag

My new Lowepro Toploader Pro 75 AW arrived today, and I must say, as a camera bag, it is a little overwhelming. I was expecting something to just replace my present “holster” which is basically a padded leather case that is designed to match the shape of a camera. This bag is more substantial, having better padding, several zippered compartments and places to attach other accessories, such as a long lens in a special lens bag (such as the Lens Case 2, which I have) or a speedlight flash. It only took me a few minutes to adjust the strap the way I wanted it, but I am having a hard time determining what I should put in the bag. So far I have put in things like a spare memory card and the backup battery. I am trying to decide if I should move the card reader into the new bag, or leave it in the main bag. The bag is intended to supplement the main camera bag, not replace it; however, having a “holster” this featured will make it necessary less often. One of the most interesting aspects of this bag is something hidden in a little pocket on the back of it, it is a little plastic covering that is tethered to the bag, much like a parachute. It is designed to deploy and cover the bag when it rains to protect the camera and bag.