Hi Richard,
We stayed last year near Marsellian Plage and found that the very short drive out of this area on the way to Sete is the most fantastic beach, which gets full up with cars, but the beach is not that busy because it is so long. We stayed at a Yelloh Village site which was quite nice, but was not cheap. This year we are looking to go to the same area but Cap d'Agde side, I have been looking at a site called Les Mimosas at Portiragnes Plage which looks to have a great pool, I have posted this on the forum to see if anyone has stayed there, but had no reply yet. I have found that I prefer this area, to that of the area around Californie, but if you do go make sure to take a trip to Collioure near the Spanish border it is beautiful.