I have a USAA MC $20K at a variable rate of 5.0% (Prime + 0%). I have had the card since Dec 07. My rate has moved down since that time.
The key - and I think it has been said on this board before is your use of their products - the more you use - the more the doors open for you.
I have checking, savings, cd, car insr, life insr, retirment plan and home insurance. I think that helps.
FICO: Eq: 785; Exp: 747, and Trans: 777.