I flew this flight in Raffles, and frankly, the "rest" area isn't worth hanging around, unless you want to chat up one of the Singapore Girls. It's right next to the galley and the loos and one of the exit doors. It's all very cramped. If you stand around there, it really just feels like you're standing in the galley and getting in everyone's way!
I never made it back to the Y rest area, but in looking at the photos of it, it looks a lot more "happening" and larger than the J one!
(BTW, don't worry about the long flight times...it goes by quickly with the excellent Wisemen system ^ )