Join Date: Sep 2006
Location: Siesta Key, Florida
Programs: UA GS4Life, AF/KL Lifetime Plat, BA Gold, AA 1MM, IC Diamond RA, Hyatt Humorist, Bonv Plat, et alia
Posts: 2,741
Don't wait until you check in ... by then, it's likely all F seats will be spoken for.
Call Continental. Pay the difference for a full "Y" fare which gets priority upgraded to "F" space available. Or to full "F" which is not much higher than "Y" in many cases.
There are no discount "buy-ups" on CO.