I saw 1 post with JFK-HND and see it might be a bit of a hassle with the HND-JFK route back.

I am thinking to go to the airport around midnight-1am and just hang out at the lounge (sky lounge) until the 6:40am departure.

Anyone done this? I just don't see the point of paying for a hotel for a few hours since I would have to be at the airport 2-3 hours before.

Also no local trains from where I would be in Tokyo running that late to get to Haneda and the taxi is way to expensive.

Any thoughts? Tips? All are appreciated. Thank you.