Another thought - check your airline's definition of "three years." With AA, it's 36 months to the day after the last activity. With DL, it's December 31 after that, giving a little extra time to extend their life with something you might have done anyway. (Just found out about this yesterday when I saw that a recent AF flight extended my DL miles to December 31, 2008. I don't fly DL enough to have regular activity there, but I have a large enough balance with them to care about not losing it.)