Isn't whether you evacuate or not something you need to evaluate under the circumstances with which you are presented? If you are presented with a situation that involves you travelling through a dangerous area to get to someplace safe, staying put can make sense. If a hurricane, tornado, etc. is bearing down on you, evacuation may be in order. When I went to sea, I often heard about trying to put yourself in the mindset of thinking "what if" about any number of thigns that could go wrong, at that moment in time. It made it easier to act in a moment when soemthing did go wrong; your brina was prepared for something to go wrong. You thought faster and could act with a clearer mind. Think about what might go wrong in your area.

I live in NYC, so thinking about what can happen here is what I try to do. What happens with a hurricane? What happens when that whole mountain in the Canary Islands slides into the Atlantic and sends a tsunami our way? What happens when we have a black out? A dirty bomb? Etc. Not pleasant thoughts, but you are not thinking pleasant thoughts when putting your bag together.

I have a bag for each of us, but we do not have kids. Still, to the extent you can, everyone having something that they can grab and go is ideal. In your circumstances, how you might be bugging out is something else to think about. Could you be going on foot, in a vehicle, train, etc.? How could your wife be going too? You do need to think about the chance that eiither her or you could be evacuating without the other, and one of you might be evacuating without your children, perhaps one of you following the other. If for example, your wife might leave with the two children and not you, have stuff packed in something that she can move. Smaller backpacks with for each of you might be the way to go.

I would have your oldest have a small pack that was all his own to fill with what might keep him entertained, and with some of his own food, clothing etc. It may help him to feel he is helping and may help you to calm him, if he gets to help in the "adventure."