Moderator, El Al and Marriott Bonvoy, FlyerTalk Evangelist
Join Date: Feb 2005
Location: SIN
Programs: SQ*G, Mar LTT, Hyatt Glb, AA LTG, LY, HH, IC, BA, DL, UA SLV
Posts: 12,026
Welcome to FlyerTalk rc_falcon02!
Transfers between the terminals are via an internal bus. Do not leave the baggage claim area. Find some staff person to show you where the inter-terminal bus leaves from.
That said, with a flight in the AM you may no be allowed to board the bus.
I have only been to the new domestic terminal once and I don't recall if the area before check-in has much in the way of seating. If it does, and if they don't kick you out of the building overnight, it will be generally safe. I wouldn't fall asleep leaving my bags unattended, but bring a huge laptop batter and some DVDs and you'll be fine. I did this in CCU last year.
Personally I'd prefer to hit the nearby Radisson hotel for the overnight.