What is the consensus on use of a SWU for LAX-LHR? An overnight flight and I generally consider the 77W seat in the mini-cabin up front to be equivalent to many mediocre F products so rarely throw in for the upgrade. Flight shows A2 today so I could get right into F. I actually used Y-C upgrades from cheapo economy fare for my wife and I for the first time this year, so wondering if I should save my CY'18 SWUs for that...