Me and my friend have just come back from Sousse. We are both girls in our early twenties.
We went to a bar/club called Boneparte, i think its opposite Legends Bar. Boneparte is really good, they play R'n B, Hip hop, funky house, and also cheesy music. Its open till 4.00am, but don't go there too early as it will be empty! Best time to go is 10.30pm. Gets packed in there with lots of tourists and tunisian people.
There is a nightclub in Sousse...i think its called Barnados! Something similar to that name. I'm sure the locals will tell you. In there, they play mostly house music, Arabic music. A lot of Tunisian people go there and it is quite big inside.
In Sousse there are 2 english pubs. 1 is called the ''Crown & Rose'' and the other is called ''English Pub''. Ideal for watching football
In Port El Kantoui there is somewhere called ''Irish Pub''. It is quite popular and very big inside. They mostly have kareoke in the evenings.
We enjoyed the places we went to and came home at around 4.00am every night. So hope this has helped!