So, about half an hour from where we were staying there is a place called Joigny. It's probably about the same size as Sens. It's full of old wooden buildings and narrow streets. A very calm and charming place. If you go to the tourist office which is on the road that runs along the Yonne river, they can give you a leaflet with a map and a historical tour of the town. It was very interesting. Joigny is on a slope so be prepared for some uphill and downhill walking.
Chablis is another town that we visited. It's about an hour's drive, south from Voisines. It's one of the more touristy places of the area because of the famous wine they make there. It's still a lovely town though and we had a nice walk along the river. It also has a little park there so we wandered through there too. If you like markets they had a big one going on there on a sunday, it was quite busy though. Of course we went wine tasting and also tried the local specialities: some Marc de Bourgogne, like a grappa, and some Ratafia which is a lot sweeter. It was really yummy and the person serving us was very nice.
These were both lovely towns and I would highly recommend a visit.