Cognac city has twohearts. The modern vibrant town with shops and a café culture. There is a very large public garden in the centre designed on the English style. Or perhaps you would prefer to tour the old town with its cobbled streets. You could visit the castle and the beautiful Charente river for a spot of boating or kayaking.
Cognac - home of the famous Brandy. Why not spend the time discovering the stages of production. Copy this link and have a look.
http://tourism-cognac.com/sejours/1-jour-a-cognac/
Like most cities I have experienced in France it is compact and easy to get around. In the summer, it is possible to take the road train to visit the main attractions. The centre is vibrant and fully of eateries, which are all lovely. However, I was taken to one just slightly off the beaten track which was traditional, ethical French fare. It is called Larty Show. It was only a small restaurant, but beautifully decorated and very calm and relaxing. Despite there being just one set menu for the day, I would heartily recommend a visit, however, it is not open weekends or evenings - so I would recommend a phone call first. We paid Euros 18 per person for 3 courses.
https://fr-fr.facebook.com/lartyshowcognac/
Cognac also hosts concerts in the centre in the gardens of one of the Cognac houses, complemented by fireworks. They have some A list bands attend so it is worth looking out for details.