Mmmmm... pineau!
Camped round here (Chatelaillon Plage)with dh before kids and will definitely go back at some stage. Really liked it. Beach at Chatelaillon is lovely (though like the whole of the Atlantic coast has big breakers). I seem to recall there was also a kids' club on the beach with a sea-water pool for safe swimming. (But wasn't looking in detail back then, as didn't have any of our own!)
Didn't find the driving too bad, ggg. We were on a motorbike, so bad driving (aimed at you, anyway) tends to be exacerbated, but it was fine. ('Fine' is possibly because I'm comparing it to Italy, though!)
We visited La Rochelle (good aquarium in case of wet days), Saintes, Cognac, Angouleme (isn't there a BD museum in Angouleme?), Rochefort and other places that have already been mentioned. Oh, and I'd definitely recommend La Venise Verte (area around Niort). You can hire boats and go on the river, or just walk alongside. Lovely. Another good place is the Ile d'Aix, a tiny island (c. 2 miles across) which you can get to by boat from (IIRC) Rochefort. You can hire bikes (no traffic) and explore, and there are gorgeous beaches too. We also visited the Ile de Re (donkeys in trousers!) and the Ile d'Oleron (busy, but a good bird sanctuary).
Don't worry, you'll have a lovely time.