My wife and I recently toured Brittany and the Loire, departing and arriving at Roscoff. During our 7 day tour, we stayed at Le Challonge Hotel at Dinan, the Mercure Borde de Loire at Saumur and the Best Western Central at Vannes. We have no hesitation in recommending all 3 hotels.
It is hard to add much to the previous good reviews. All the staff very friendly, professional and attentive to our needs. We had a room with a balcony at the front of the hotel, nevertheless there was very little noise. The room was well appointed/maintained and very clean - WiFi a bit slow.
We did not eat in the hotel, but the restaurant was well frequented which would seem to be a good recommend.
The hotel is ideally situated for access to the old streets of Vannes which in turn provide for a pleasant walk down to the quay.
Parking in France can often be a problem and so we found that the underground car park to be quite good value at 9 Euros per day, especially for protecting our car which was groaning under the weight of copious bottles of wine. The French seem to believe that a car bumper is used for literally for locating adjacent cars.
We eat at Brasserie des Halles and Le Sinagot Bar-Brasserie - see reviews.
The aquarium and butterfly farm are a pleasant 20 minute walk along the quay, but it is debatable whether the 18 Euro entry fee is reasonable.