Right; I do rather like Citi's method of having a visible credit limit in addition to the "credit guide." Since regular Amex CSRs cannot tell me what the limit is on a charge card (and deny that such a thing exists), I consider the limit to be hidden. Account Services will confirm that there is a hard limit and the amount of the limit. Nor would they negotiate an increase on a new Gold Rewards Plus charge card with a horribly low limit (despite having about 25 times that amount in combined available credit on various Amex credit card products, which I was happy to have reduced if they could increase the limit on the GRP.) I was told the only thing I could do was wait 6 months and the limit would "probably double" after some activity, and continue to do so in the future—it more than doubled after around 3 months.

Anyways, this is kind of off-topic and I've complained about it at length multiple times in the Amex forum so I'll be succinct... So, Amex lets you reallocate credit lines between credit card products but not with a charge card product, and Amex will issue larger credit lines at first then issue cards with smaller credit limits once you have several cards with large credit limits. Let's say you're an Amex customer with good credit and apply for 4 new cards over a few months. Amex decides that they will give you $25k, $25k, $10k, and $5k limits on these cards in that sequence. (I believe that Amex will not provide a limit of over $25k on a new credit card without submitting financial documentation. You can reallocate credit to a card and take it past $25k easily enough, but I've gotten the feeling that you're setting yourself up for a financial review by doing this.)

Example 1: The first card is a charge card, the last 3 are credit cards. You now have a charge card with a $25k "limit" and 3 credit cards with $40k in limits that you can shuffle around as you like.

Example 2: The first 3 cards are credit cards, the last one is a charge card. You now have a charge card with a $5k limit that cannot be increased immediately, so you can't spend more than $5k in a 2 month period unless you feel like paying the card off early. Several months later the limit will perhaps go up. You have $60k to shuffle around amongst the credit cards, but it sure would be nice if some of that could go to the charge card!

I know I'm making some assumptions here, but based on my experiences I'm fairly certain this is one piece of how Amex assigns new card limits. I have quite a few Amex cards between personal and small business, and after the first half dozen or so noticed progressively lower limits on new cards. The new GRP came with a limit that was roughly equal to a couple of Amex credit card products I'd applied for around the same time. Older charge cards and credit cards both came with much higher initial limits when I had far less open credit with Amex.