Hello friends,

I haven't done this before, so I appreciate your strategy help.
I'm flying from LAX to ZUR in mid November. United has flights that go through EWR, ORD, and IAD. The seat maps for business class on the international segment are about 1/3 full from all three connecting airports. In expert mode, I'm seeing J3 available on the EWR-ZUR leg, J9 available on the IAD to ZUR leg, and J7 available on the ORD-ZUR leg.
I'm wondering what my best strategy is for getting a decent cash upgrade offer. Does anyone have any wisdom about which connecting airport would be best?
Should I buy a cash economy ticket (refundable for 24 hours) and see what the immediate cash upgrade purchase price is at checkout?
Should I reserve a saver economy ticket using miles and wait to get a cash upgrade offer?

Thanks for any suggestions. Just to make things exciting, I need 4 seats, which I know will be tough. Thanks for your help!