I'd like to fly in by Swiss arriving at midnight and then take Air India flight to CCU at 6:50am.
I have UA*G card. Does anyone know if I can use Air India lounge? Do they have shower and places to sleep? I can't find this info on airport website. They write that it's exclusively for AI business class.

Alternatively, I see something like Plaza Nap&Shower. Did anybody use this? How much does it cost?
I prefer to stay in transit area and not leave airport to outside hotel.