You wont have any problems using other hotels facilities. As for bars not so good - it is a muslim society. Although tourists are catered for, the bar culture as we know it doesn't really exist.
Certainly in the larger towns such as Sousse and Monastir there are bar restaurants to be found. Don't assume all restaurants serve alcohol though. Some don't as a consequence of their owners religon. One of my favourite restaurants in Monastir doesn't serve alcohol at all, some don't on Fridays but do other days. Check before you order is my advice.
If you want to buy for your own consumption on a Friday the Monoprix supermarket doesnt sell alcohol but the Supermarche General in the Medina does! Just keep your bottles out of sight when entering the hotel. Understandably they would rather you bought theirs. Oh and if buying cans of lager in a supermarket , make sure you dont get the NON ALCOHOL versions by mistake.
have a fab time
Dorra