...with my DS going next month with the band. I haven't completely made up my mind, but I have considered a couple of things. I haven't ruled out travelers checks, but not convinced, either.
I checked with WDW and anybody can use the Disney Rewards card that we earn with the Disney Visa. I specifically asked about teens and they said it was fine, since no ID or pin required. That being said, the idea of losing the card is a little scarey, but it is a possible alternative to cash.
Another thought was a pre-paid mastercard. One of our banks offers this as a gift card. It looks and acts just like a mastercard with a number and all. It does not have a name on it, so no ID or pin, but can be used anywhere credit or debit cards are used. I also checked about their use in WDW and was told they are accepted. I walked in to the branch and purchased several for Christmas gifts and they worked out fine. They do, however, have an expiration date of about six months. And like the Disney Rewards card, there is a phone number to call in case of loss. I've thought of splitting his funds between two cards, so that if one is lost it wouldn't mean the possible loss of all his funds!
Perhaps you have a bank that offers this?
I may end up doing some combination of the cards and cash for DS, but still thinking about it.
Hope this helps and best of luck!