I'll take your word for it that it's tough to upgrade from Y to C on LAX-JFK, but I always upgrade from C to F on UA. Never been denied. The same goes for IAD-LAX on the 777 or 747.
And yes, on the NY flights I often see someone recognizable (though I don't watch much TV) and on the D.C. flight I often see and hear (they are windbags) politicians.