Not done Y in ages too but a few suggestions would be to take some ear plugs as I don't think you get any in the socks/toothbrush amenity bag.

When I flew Y to HKG a few years back on the £136 deal I found I managed to blag a WT+ upgrade on the way out and on the way back HKG check in were offering upgrades to WT+ for 1500HKD I think. Worth asking for the return trip if this is still available.

Benefit of Y is that if the flight is not full then you can lift the armrests and lie out. Can't do this in WT+.

Also bring some sleeping tablets to help knock you out and sleep.