There is not much of amusement in Houmt Souk. I haven't seen any nightclub or dicoteque inside the town. There are no local women or girls sitting in the cafe-bars, it is exclusively men's zone. Must be disconfort being young female tourist who is sitting in the local bar because locals are openly and permanently staring at her.
I was lucky when visiting Midoun, small place in the middle of the island. There was performance in the local open air theatre, presenting the traditional Djerba wedding ceremony. It was very exciting and colourful supporting by the Tunisian music which is rich of rhytm.
More about in my traveloque.
There is a cocert hall in Houmt Souk, build in the shape of old Greek/Roman theatres. It is situated on the seashore, right next to the fortress of Borj el Kbir. When I passd by, last night, there was a concert and it was overcrowded by the locals, many of them standing outside the arena and listening the music. It is where most popular local and international stars have their concerts when in Tunisia.
In the end of the afternoon, why not have a rest in a local café in Houmt Souk, the capital of the island and sip a coffee or a mint tea ? That will be much more interesting to be in the middle of locals than to stay in the lobby of your touristy hotel ! The only thing is that they do not serve alcohol though alcohol is an Arab word !
The tourist zone in the northeastern corner of the island,offers good night life, which is dominated by Western travellers. Most of the hotels have their own bars, clubs and theaters. There is also a Casino (Pasino)