I don't remember the deal on the purpose field, but most people try for the Plat Cash Rewards, which has the 5% back on gas, 2% on groceries from grocery stores (as opposed to from WalMart, etc.) and 1% on everything else. (Just dropped down from 1.25%.)
The AmEx was started a few months ago, and you can read discussion about it
here.
And the PenFed site has a pretty clear breakdown of the cards
here; don't know if you've seen it.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007
