To be honest, they’ll enjoy whatever you do 🙂
We did a Eurocamp style place in France last year for 2 weeks, kids (7,5 & 2) loved it. Doing the same again this year, albeit a little further south. We’ve also taken them to Spain which they also enjoyed. For me though – plane + kids = nightmare, car + kids = less of a nightmare.
One thing to note if you do go to Western France, the Atlantic is much colder than the Med. Real shock for my boys last year when the sea wasn’t warm enough to just swim in for as long as they wanted. Wetsuits this year 🙂
We went to this place last year & it was great:
https://www.lagrandemetairie.com/en/
Here this year:
http://www.campinglecurtys.com/