Hi Gavandi - we've done both Brittany and Ile de Re. Both are fantastic.
For Brittany, I recommend this great campsite;
Campsite in Douarnenez in Brittany - nature holidays - Huttopia We've stayed in the few under the same name (used to be Indigo, now Huttopia) and they have all been brilliant. I run a bit and the coast path to the right (as you look out to sea) was amazing.
And this site is also a belter and be sure to visit Concarneau nearby;
Camping Concarneau - CAMPING LES SABLES BLANCS **** - Bretagne, Finistère Sud
Good pool, restaurant and location.
And onto Ile de Re - absolutely loved this island and I think we'll return next Easter.
For mega facilities and a good location near the lovely town of La Flotte (we preferred it to the slightly chintzy St Martin) this is a good site;
Camping ile de Ré - CAMPING LA GRAINETIERE - Charente-Maritime It's not cheap but has a great pool, bar and decent restaurant and is a good base for cycling.
We then tried a couple we weren't that sure on then stumbled in this amazing Municipal (so cheap) site - cracking value, near a load of good restaurants, pretty much on the beach and well placed for all sorts of fun;
Le Remondeau – Un site utilisant WordPress
It's quite basic but we prefer it like that.
We had 8 days of uninterrupted sunshine too; really enjoyed it.