We are open to suggestions as I have never been that way before,I would like to celebrate my 50th in somewhere sunny but not to busy,I dont drink a lot due to my job and I will have my 14 year old son with me (and my wife of course !) So sea side is perfect but with something to keep my son interested and not to expensive. We are planning 5 days there on the way back from Spain then heading home.
Depending which side you're crossing the Pyrenees....
On the east side, Carcassone is a nice old town/city. The Perpignan is OK too. Personally I'd goa bit further into France - follow the motorway to Arles or Avignon. Plenty to see, good history, nice countryside and not so expensive as the coast.
On the west side we quite like the area around Archachon. Beaches are ice and sandy, and being the Atlantic coast the rollers are quite good if you like that kind of thing. You can also tour around the vinyards south of Bordeaux too.