I consider my BoB bag as two separate items. One is an actual backpack with hiking gear, water, food, etc. (although there is not enough water or food for 72 hours). The other is an attache-type bag with some survival items, but really more of the day to day carry, including dayplanner, etc.

The reason for having two bags is that if I decide to go hiking, the backpack isn't filled with paperwork. And if I'm out working, I can just carry the attache bag and be content with the survival kit in the car trunk.

If it got so bad that I truly had to evacuate or "bug out", I'd be carrying the backpack on my back and sling the attache bag over my shoulder. I'd have my personal information and important stuff, along with some water, food, survival gear, and navigation.

Not to mention a pair of hiking boots on!

Ideally, though, I lean towards being able to "bug in" and stay at home. I easily have 72 hours worth of supplies that way. If something major happened, such as a natural disaster or man-made disaster, bugging out would be my last choice.