Many people here like the Starwood Amex with low annual fee, and the points can be converted to miles.

I like the Hilton HHonors Amex, NO annual fee, points are as good as miles (can be redeemed on many airlines), and points can also, of course, be used for hotels - Hilton, Embassy, Doubletree, Hampton, and more. Hilton also offers a Visa Signature with no preset spending limit, but you earn 2 points per dollar instead of 3 on the Amex.

Many more details can be found at the Starwood and HHonors website, and by searching the flyertalk forums. There are many good threads on the subject. Also, check out www.creditcardgoodies.com.