I've heard of a hierachy very similar to what "knowitall" descibed above, except perhaps numbers 3 and 4 are/were reversed.

And last December, as a Gold, I could not clear for FC, even as I watched at the desk as Silver Elites had their BP's issued ahead of me!

As I happily noted, there were actually many free FC seats to be seen upon boarding and a last minute upgrade was done for me and another 4 people!