Originally Posted by VegasGambler

I'm doing something similar in a couple of weeks.

SFO-JFK, overnight (10hr) layover on an AS ticket.
JFK-SEA-NRT-BKK on JL stock. JFK-SEA is on AS, the rest on JL.

I don't plan to get a hotel in NYC -- just head to Manhattan for few hrs, and back to the airport by 5 or 6 am. I'd rather not have my bags in NYC, of course.

Do I just explain all this at check-in in SFO? I assume it shouldn't be a problem. I have AS status, and the JL ticket is in business class so I have plenty of baggage allowance.