Well, you have a lot of options for nightlife in Delhi like Mocha Art House, Little Owl Café, 24/7, E&Y Dhaba, Pandara Road- India Gate, The Booty Call, Comesome, Hard Rock Cafe. If you have a car, you can go on drive and allow your hunger to settle down by the roadside food stalls. You can check Cultural nights and exhibitions across the city that are generally organised at night. Happy nightlife :)
Jaipur is famous for forts and hence Amber Fort and Palace, Hawa Mahal - Palace of the Winds, Sheesh Mahal, Jal Mahal, Rambagh Palace, City Palace, Nahargarh Fort, Jaigarh Fort, Sisodia Rani garden, Central Park, Jantar Mantar Observatory. However, a foodie and shopaholic can’t be happier at any other place. Chokhi Dhani for foodies and Bazaars for shopping are best that Jaipur provides. Apart from this, you can visit festivals like Jaipur Literature festival and many others.
Well, yes, Mumbai never sleeps. You can do a lot of things even at night in Mumbai. For party animals - the clubs in Mumbai are awesome for partying. For those who love to drive - you can enjoy the driving experience on sea face side from Marine Lines - Worli sea face - Bandstand / Carter road. For those who crave silence and simplicity - you can enjoy a cup of tea from the local chai wala which roam on cycle and then take a late night stroll with your favourite person. Apart from this, you can also visit colaba side gateway of India and Fort enjoy old Bombay there. If you are a foodie, you can visit Haji Ali juice centre to kill your hunger it is mostly open by 2 am or enjoy gola , sweet corn and many other street food and marine line or Khau Gully.
Kolkata has the best nightlife compared to every other metro city in India. You can go to Dublin, The Park, Aqua, Lytton Hotel and Someplace else Pub. Tantra is one of the most happening luxury bar and nightclub in Kolkata. You can not find a place more busy than this in whole city at night. Most nightclubs are apt for every type of person and they have music, disco, hip hop, trance, Hindi pop and remixed Bhangra which suits all type of people.
Kolkata is a place to visit for all kind of people. Dikshaneshwar temple, Science city, Victoria Memorial, Eco Park, Ganganagar, Nandan Kanan, Birla Science and Technology Museum, Kalighat Temple, Nicco Park - an large amusement park, Howrah Bridge, tram ride (not a place but you must give tram ride a try), Buddhist Pagoda, Belur Math, Nandan, Kumartuli, St. Paul’s Cathedral, Birla Temple and a few places to point out and of course Durga puja which is best and most celebrated in Kolkata (whole West Bengal as a matter of fact)