TBIT at LAX after 7 p.m. is a zoo. Many westbound flight to Asia leave late at night. Check-in lines snake out the front doors of the terminal and onto the sidewalk (baggage is screened before check-in and this is the bottleneck that creates the long queues). If you snag that upgrade, find the business class screening queue (or use a skycap to get you to the right place), otherwise you could spend over an hour just to get to the front of the line. You will still need to get to the airport 2-3 hours before departure (less for business class, more for economy class). I hope the new lounges are finishes, otherwise everyone is crowded into one lounge on the mezzanine level, located before pax screening, which is not convenient at all. I avoid LAX like the plague.