I originally started flying Northwest seriously back a few years ago when, in response to a letter I sent them, they comp'ed me to Gold status based on my travel volume with another airline and my commitment to fly enough to qualify on my own for the following year. At the time, Gold was their only 'elite' level.
I would suggest that you re-send your letter. Be specific on what you want and what you plan to do in return for their granting you elite status. It's a two way street. Be sure you enclose copies of any verifying credentials that substantiate your current flight activity and include your phone number as well as your mailing address.
Good luck!
------------------
/swaggie