I do not want to get stuck paying a higher rate, thus my reason for looking for a coded rate

I don't mind taking a small risk with the rate, I just don't want to take a large risk that the rate will not be honored.

Using that code at other Marriots doesn't give me any lower rates, just that particular Residence Inn.

Someone mentioned calling to ask about the rate code--is that call to the central reservation # or the hotel itself?