Via this post at WorldChanging I found two excellent older posts:
A subset of the rule that the Elect will survive is that survivalists survive, that bunkered individuals or remote farming communities or whatever have an edge, and that when the crazy starts, it’ll be the people holed up in the hinterlands who will survive and that the rule we can observe all through history — which is that these people are simply prey to larger, better-organized groups — suspends itself for the duration (unless a savior is needed to fight off the Humungous and his mohawked thugs or something — see #2 above).
But real apocalypses are sordid, banal, insane. If things do come unraveled, they present not a golden opportunity for lone wolves and well-armed geeks, but a reality of babies with diarrhea, of bugs and weird weather and dust everywhere, of never enough to eat, of famine and starving, hollow-eyed people, of drunken soldiers full of boredom and self-hate, of random murder and rape and wars which accomplish nothing, of many fine things lost for no reason and nothing of any value gained. And survivalists, if they actually manage to avoid becoming the prey of larger groups, sitting bitter and cold and hungry and paranoid, watching their supplies run low and wishing they had a clean bed and some friends. Of all the lies we tell ourselves, this is the biggest: that there is any world worth living in that involves the breakdown of society.
A related older post: The Outquisition
I mostly look to the periphery for an idea of what dystopias will look like, so my favorite dystopian movies are movies like Salvador, Hotel Rhwanda, and City of God. One sci-fi dystopia that I like is Children of Men, because it seems to be based very much on the reality of the periphery.