Post-trip DP. Ended up taking the flight with 15hr layover. Bags checked all the way. Transfer went smoothly with next-morning BP. No problem getting into Pier J the afternoon before. Lounge closed at 1:30am. Slept for a bit on a nearby bench, came back after opening at 5:30am. Did not try the overnight Plaza Premium - has bad rating saying long line, no beds, etc.
There is a good # of beds in Pier J - maybe 20. They are very comfy for upright sitting but not as much for flat sleeping. No pillows in lounge - I used a blanket as pillow. MH KUL lounge has better beds for sleeping.
Maxing lounge use helped justify the J award cost on this intra-Asia flight.