Nightlife in Nice ise very lively. Nice is one of the most active cities in French riviera in terms of social life. Most of the people prefer to hang on the beach at nights.
Some of the suggested bars in old town were LES 3 diables and Ghost but they are not so good actually. Try Waka Bar for the nice dj and dancing crowd.
This place also has an entrance from the seaside road. Therefore you can get your drink and also stay at that part too.
An aperol-spritz is 8.5 euro
FB of Waka Bar: https://www.facebook.com/WakaBarNice/
More info about night life: http://en.nicetourisme.com/time-out-in-nice