Question for the group - I am flying LAX -> NRT -> SIN and return. I am on a K fare and the W fare was significantly more, so I can't use my GPUs except for the NRT -> SIN and SIN -> NRT.

Looking at the reservation I am offered 30k miles + $600 copay for upgrades all the way through, though it is waitlist only. I'm willing to pay this if I can get them all the way through, but not only for one segment. Any strategy here? I suppose I could always ask to get downgraded at the gate if the LAX/NRT doesn't clear?