US offers 50% bonus miles to the base level (Silver) members and 100% to 2nd & top level (Gold and Chairman's) members, and it seems for term of the status and not just until the end of the qualification year (e.g., February for CP (and AA?))

IIRC, BA EC does offer a bonus to their elite members but of course getting elite status on BA is difficult if you don't pay full fare.

[This message has been edited by terenz (edited 06-01-2000).]