Has anyone here had success on a PlusPoints upgrade on the SFO-BOS route? Doing a trip in May with my elderly parents for my son's graduation at Boston University. Seats wide open now but I'm sure that will change. Got a decent fare and the upgrade cost is currently about $650 each way/person. Just wondering if I should just pay the upgrade fare and be done with it. They are willing to pay for the upgrade since this will probably be their last trip across country.

Thanks in advance for the advice/success rate!