Advice please!

Hi
Am traveling out to Chicago in PE on P class tickets. I understand that these usually are not upgradable using miles however do you think it is worth a call to FC a couple days before to ask or wait until at the airport. The flight is on the 17th June and there seems to be good availability for UC reward seats.
Any thoughts?
Thx
Am traveling out to Chicago in PE on P class tickets. I understand that these usually are not upgradable using miles however do you think it is worth a call to FC a couple days before to ask or wait until at the airport. The flight is on the 17th June and there seems to be good availability for UC reward seats.
Any thoughts?
Thx