Ok..."worldwide and the image would remain in our archives forever and could potentially be used again for a different story published by American Express Publications and or syndicate".
Worldwide, ok.
'archives forever' ? I'd offer a 12 month license to begin with, see how the image performed and, just as important, how the client behaves.
The syndication bit worries me.
If the image is syndicate-able then the client believes the image may be worth more in the long term in the wider market.
That may simply be an inexperienced employee misinterpreting/representing.
If the initial client is hot to syndicate then let the initial client market the image *short term* for you and, when the image is more widely known AS YOURS, you can offer out further licenses direct to other clients.
Personally, from experience, and without knowing all teh facts (obv) I'd offer a clearly defined single use license and see how it goes both with this image and this potential client.
The fact that they are still talking to you is a good indication of their understanding of licensing, their idea of the commercial value of your image and the fact that your image is - clearly- of a commercial quality.