Hah - my sister is 43, and I hung on to her pass too. (most of the time, anyway) and you can just FORGET about those kids (hers and mine) - they lose everything....
I have a little-little leather wallet/ID holder with a key ring attached to it. I keep the passes in there, and a little loopy-wire-thingy attached to the key ring on one end, and my belt loop or fanny pack on the other. (The loopy wire thingy sort looks like a telephone cord, and it is for keys. I picked it up at Wal-Mart.)
When we passed through the gate, they handed them back to me directly, ("that's one, that's two....that's six - okay, we got 'em") For FP, my son and I would go, and keep count of them.
One suggestion - those magnetic strips can be very sensitive and get corrupted easily. Keep the passes in the cardboard sleeve they come in. I put all six together, no problem, but as soon as one or two went into the leather wallet with out the sleeve protection, they would get messed up. I think the leather has some static electricity. If they do get corrupted, they can be replaced at Guest Services at the parks.