Hi Bevotex

Hyatt GP allows Diamond Members 4 PM checkout so I reserve the night before , which works perfect for me. I get in from SGN at 6:45 , for an 8 hour layover. I'm considering checking my bags all the way to LAX and not have to wait for baggage at ICN.
My plan is to catch the shuttle at gate 3 or 13, which I've read runs every 15 minutes and be at the Hotel by 730 latest. I will have to return somewhere around 13:15 to be at the airport approx. two hours before the LAX A380 flt. @14:50
I've never done this before here. I have read to try to get a room in the newly renovated West Tower, as it cuts down on walking from the front desk, to your room and club floor if you have access.
I don't know if you have status with HGP but if you do then choice number one is your best choice in my opinion.