Look into the latter quickly. Per threads elsewhere on FT, AA has apparently announced that starting a few days (April 8?) it will only allow you to use miles for non-flying if you have a balance of 25k or more (unless you have status). I don't know if they're the first or if they're reacting. But if other airlines follow suit, you may soon have zero use for small balances. Thus if some of your airlines have no such limit now, you may want to identify which ones you'll want to do the donations from and do them sooner rather than later.