Settlements should be kind of sparse (at least if it was a really<em>good</em>apocalypse, not like that Mayan stuff that went down in December).  They might have to travel a bit to find one.<br/><br/>Might be some 'hot-spots' of whatever killed off civilization.  Mutant critters are always good.  People are probably suspicious of strangers and weird beasties.  Maybe they find the airship interesting?