Would second the recommendation for Dinard. It’s an old Belle Epoque seaside resort, somewhat faded glory but with some amazing old mansions (think Newport RI). You can also nip across the bay in 15 mins to see St Malo which is busier and has more tourist sights.

We ate at Castelbrac (Michelin 1*) but did not stay there. Great location and views. Restaurant was good, if unremarkable.

La Baule is a lot more developed. Also be aware the road network in Bretagne is not as well developed as elsewhere in France and in summer journeys can be very slow. That said, it’s a wonderful place.