Use the Sheraton Starpoints card as a base:

* No fee
* $1 = 1.25 miles on virtually any airline
* No expiration

To improve on this:

* Special privileges e.g., car upgrades, elite level membership
* No annual cap on points earned

I am not interested in a dollar-based card as I tend to maximize my miles and use them for international FC travel and upgrades worth far more than 2 cents/mile.