For my bag of tricks, 1xCR123, 4xAAA, 6xAA. For my BOB, 4xCR123, 4xAAA (the almost-EDC graphing calculator can stay behind!), and 12xAAA, along with the BOT's cells. Right now, they are ziplock packed, but I'm thinking of getting a small Pelican or Otter case and cutting a custom foam spacer for it.

And I never feel like I have enough AAs. Paranoia, no doubt, as the only things I carry that need them are MiniMags which will soon be LEDed, and a tiny radio.