Few people who plan to "bug out" when the SHTF have no real destination in mind.  Most of these folks aren't gonna make it.  Heck, traveling during such an event is a bad idea altogether.  Ideally, you want to be LIVING in your "retreat" when SHTF.  You can live out of a backpack for a week or two, but soon you will need real shelter and a place for tools, cooking, etc.

For those lucky enough to have friends/relatives in a remote rural area, and assuming they would welcome you during a SHTF scenario, all you have to worry about is being able to get there.  Probably the most important thing for you would be to ALWAYS be ready, with your bug-out gear packed, spare fuel, etc.  You will need to be on the road immediately after "the event", because it won't be long before everyone will have the same idea, and the roads will be clogged with people trying to escape.  Your vehicle had better be reliable, have a long range, and preferably have some off-road capability.  Those with enduros (street-legal dirt bikes) will probabably have the easiest time on or off the road, as they can get around traffic jams easily.

If you have no solid, prearranged destination, you are better off staying home and being prepared to defend your home as best you can.  Assume the roads to be impassable within 24 hours of the event.  Assume little to no ability to resupply food and water, much less gas and electricity.  And assume that others will eventually come and try to take what you have.

There are lots of good books on the subject.  One of the better ones to get you thinking is [i]Patriots : Surviving the Coming Collapse[/i] by John Wesley Rawles.

http://www.amazon.com/exec/obidos/ASIN/156384155X/ref=sim_books/105-7919477-9819910

-Troy