Definitely go to Aqua Java and sample some good shisha with a sophisticated coffee, and go to the Shisha Bar for some proper bollywood/dance music for a boogie and good crowds (expensive drinks though).
Also try the bar 'something else'- good for travellers wanting to hear some live western music.

Part Streel in Kolkata has the best nightlife in Eastern India. Hit this spot only if are staying in Central Kolkata