Well, I don't know how the USA division operates on this specifically, but when I got my first AMEX 2 and a half years ago, in Spain, I was just under 23 and first applied for the Gold Credit card (this is Spain's only credit card product as they focus primarily on the charge card business in that market) and got approved for 2.000 €.
After a month or two I decided I loved AMEX and decided to apply for a Green charge card, and was declined.
I was devestated and remember thinking to myself that it was odd and I couldnt understand the rationale on why they would approve me for a product which I am able to pay over time and make bare minimum payments on each month, but would not approve me for an account that must be settled in full each and every month. Customer service could not give me the reason as to why they didn't approve me.
Anyway, about 9 months after having my Gold Credit card and showing them that I was good for it, I skipped Green alltogether and they did approve me right away for a Gold charge card. I tried to get Platinum right away but at the time I was 7,500 € shy of the annual Platinum income requirement (they do ask to see income verification in Spain) but they did qualify me for Gold.
Now at first, it wasn't a cakewalk because they would cut me off at low spending amounts (1200-1500 €) the first few months, but I think once they saw that I travelled heavily overseas and used the Card for conferences, events, and launches quite liberally, they kept gradually increasing it month by month. Actually, I had to call them once and very firmly tell them that if they wanted, I would make a mid statement payment but that I needed to have access to the card for work expenses, and I think they sensed I was a little ticked.
To make an already long story short, after a year of Gold I graduated to the Platinum Card (Spain) and the Platinum Card (ICC-Dollar) as well as several AMEX credit products and my relationship with AMEX (in all countries) is great as of now.
I think worldwide with the charge products, AMEX is more stringent and still wants to maintain a bit of ¨cache¨ and an air of exclusivity on them. I understand that in the States AMEX cards are substantially the hardest cards to get, and that the co-branded credit cards like Starwood and Delta have lower credit requirements than the other AMEX products.
My recommendation is just to hang in there for a few more months and continue to build your relationship with AMEX. Once you get in good with them, you are all set, and you can do this with ontime payments and heavy card useage.