Well this is my first post.
Sorry it's long

I hope the following helps. I have been a amex member since 93. After a year with a green I called amex cust serv just asked about the gold card and got it. I didn't charge alot back then $500.00 a month if that. A year after that I called and just asked about platinum,
I was told invitation only, I was polite and
let them know I expressed interest, nothing more. 3 months later I got the invite. I was only charging a $1,000 or so a month when the invite came. I have had platinum ever since and charge everything now. I just found out about Centurion black so I made another call. I got transfered to a black card rep. She was extremely polite, I expressed interest and asked the benefits.
She went over the whole list.

Companion concord tickets.
Preferred room upgrades.
Your own personal travel consultant for reservations,upgrades and special desires.
Invitation only events at major department stores, galleries, show openings, etc.
Use of the private dressing rooms and private shopping area's of bergdorff goodman.
Easier point levels to achieve for rewards.
And other travel related ad-ons.

After that she asked if I'd like to be considered for the card. I politely answered
yes, that would be nice. She said they will be sending thier next batch of invites late
August and to start checking the mail around then.

Now I don't charge $100,000 a year,but I'm willing to bet
I get a invite in early September.
I do travel and even charge my grocery's. But I think it's not just the money figure. My charges are very diverse, anything and everything that's what got me the platinum card.
Platinum has been good to me especially at a couple hotels in Montreal. Upgrades everytime.
Call and be super polite , not pushy, not demanding. Let them ask you. Just a simple
inquiry with a touch of class in your voice
worked for me in the past.