Hoarders, since your miles have significant economic value (e.g., $38K for my 1.9M-mile stash with AA), don't forget to designate a beneficiary for your miles in your will or trust!

I have been involved in two situations where miles (and upgrade credits) were bequeathed -- after the deaths of my first wife and my father-in-law. In both cases, AA was very nice and supportive and merely required a signed statement that so-and-so was the legal beneficiary of the miles, but it would be better to have it explicitly mentioned in the will or trust if you needed to back that up, especially if the beneficiary isn't someone "obvious" (like a spouse).