Zaqatala is a city conveniently located along the road between Sheki and Georgia. Near Zaqatala there is the village of Car (or Zar) which is also recommended by the guidebooks.
Zaqatala is a pleasant city with some historical highlights (the walls of a fortress built in the 1830s by occupying Russian forces, the ruins of the Armenian church of St George), a nice mosque and a nice park. But that's it more or less. And the compound of the walled fortress/castle is a bit messed up, because instead of preserving it, they have built all sorts of modern buildings inside. Disrespect for history. However the city centre is nicely set up with a park, shops and a cafe. It is possible to explore the points of interest in about one hour.
How to get to Zaqatala
Zaqatala is along the road from Sheki to Georgia and can be easily visited, by breaking the journey by car.
There are a few hotels in and around Zaqatala, bookable through the hotel booking portals.