<<20K for 25K AA miles. That's a 20% bonus>>

25%.

I second the suggestion to start with the Starwood Preferred Guest credit card (issued by American Express), because the annual fee is low (waived for the first year), and the number of airline partners is large. This gives flexibility in case you change airlines after a few months. You can use the card and redeem the points even if you never stay at Starwood hotels (Sheraton, Westin etc).

However, it's important to always carry a second credit card from a different issuer. This assures you have a way to pay if your primary card is declined for any reason, including a failure of the issuer's authorization system. If your primary card is an American Express product your backup should be a Mastercard or Visa because those networks offer somewhat wider acceptance. If you plan to fly American you could use the AAdvantage Mastercard issue by Citibank, or for more flexbility Diners Club Mastercard also issued by Citibank.

dennis