Join Date: Sep 2006
Location: Princeton, NJ; Lviv Ukraine
Programs: UA 3.6MM, AF/KL Lifetime Plat, BA Gold, AA 1MM, IC Spire RA, Kimpton IC, Marriott Plat, et alia
Posts: 2,732
I maintain both FB and CO platinum; FB I use for upgrading AF and KL flights ... I love AF's F class where it's offered.
But all in all, I think you get more leverage by achieving "platinum" status on a second (and even third) alliance.
I find having top tier on all 3 gives me the greatest flexibility, and I can fly virtually any airline in the world and get elite treatment.