Realistically I only face the threat of earthquake, and chemical, biological, or nuclear attack or accident. (I suppose there is some risk of volcanic activity also, but I think there would be ample warning of that.)

Assuming I have survived a quake then I stay put. I have 30 days worth of supplies stored seperately from my house. Within hours of a quake relief would be pouring into the affected area. (I know, it is not wise to rely on outside help--and I don't--but it would be silly to pretend such help would not be coming.)

In the case of NBC incident, then for the first few hours I am going to be glued to the radio. How would it be to immediately hit the road, only to find out the wind has shifted? If practicable I'm going to make damn sure what the situation is before I head out. This would give me a chance to coordinate with family as well.

If I absolutely, positively have to leave, and the roads are definately passable, then I hook up the travel trailer and go. If the roads are questionable, then I hook up the ATV's behind the truck and go. And if the roads are impassable, then I fire up the ATV's and avoid the roads entirely.

I would plan on returning home as soon as I could unless some sort of contamination made it impossible.