Najayo and Palenque are completely different than the beaches to the east. The sand is greyish, there is hardly any development apart from the beach restaurants, almost only Dominicans that go there, all in all a very different experience from the beaches in the east. San Cristobal itself is an interesting town, with the cathedral and Trujillo's 'palaces'. The fifties concrete palace Casa del Cerro has just been renovated and looks completely different from the crumbling hump of concrete it was half a year ago. If you're into that sort of thing there's a former mansion of Trujillo on top of the hill next to Palenque beach too, deserted and without any guards, and you can walk around in it and see how a Trujillo mansion looks like, after it has been stripped of everything of value of course and left to crumble away.