Of the places you mentioned, Chateau Richeux and Manoir de Lan Kellerec are fantastic choices. Both offer stunning ocean views and great food nearby. Chateau Locguenole also looks charming, and La Cana Casa is perfect if you're looking for breathtaking sea views.
When I'm traveling, I prefer to stay somewhere similar to Broadbeach hotels, where I stayed when I visited Australia. They had spacious rooms and great amenities, which made my stay super comfortable. For sightseeing, don't miss the Pink Granite Coast and the medieval town of Dinan. For food, try the local crêperies and seafood restaurants.