I found this place while looking for something similar to La Grange du Moulin, which worked so well for us last summer with our two boys (aged five and two), and we weren't disappointed.
Emerald Coast Gites is run by Lesley and Simon - a British couple - and they've thought of everything you need to holiday happily with small children. The gites are comfortable and have all the kit you need, plus it's safe. The car park is separate from the gites and outdoor area so there are no cars on site, there's a pool and a toddler pool (both fenced), a large fenced garden full of toys and games for all ages, an undercover area with a mini soft play, and a wii for older kids.
There are seven gites, so there were plenty of play mates for our children. The weather was lovely and there is lots to do in the surrounding area - beaches, historic towns and cities, aquariums, zoos, castles, etc, so we were spoilt for choice of things to do each day. There is a bar on site and Lesley provides four evening meals each week, if you can't be bothered to cook. There are also frozen meals available if you prefer to heat something up in your gite.
We had a very happy and relaxing time and I would go back - although we probably won't as we never go back anywhere - preferring to try something different each year. I would recommend it to friends though and it's very easy to get there - Brittany ferries to St Malo and flights to Dinard or Rennes are all within an hour's drive.
My only caveats would be:
1) There is a chicken farm literally next door and if the wind is blowing in the wrong direction the smell is awful (on the subject of smell, Brittany in August is full of farms muck-spreading, so if you're sensitive to bad smells I'd go at another time!)
2) I was surprised by how many older kids were staying while we were there - there were more in the age 7-12 bracket than below, and this is apparently common in the school holidays.