I have had lots of credit cards over the years. The only card that I had that earned miles for convenience checks was the Bank of America USAirways VISA card. It happened 3-4 years ago and only over a 3 month or so period. Write a check (no transaction fee), earn 1 mile for every dollar you write the check for. I got three checks each month for 3 months. I ended up getting about 35K miles and paid little or no interest since I could make a payment on the account online even before the check was posted to my account. It seemed too good to be true and apparently it was - I have never seen such a lucrative offer since.

John