We take cash. We have no credit cards, so that option is out.
The debit card is great but there are many fee's associated with it. I used it our last trip in Downtown Disney. I took out $300.00, the fee's for using that ATM were $4.75. Remeber too, that your debit card will have a limit you can take out per day. Also, did you know that if you have "many" high transactins in a row on your debit card, many banks will freeze your account, until they verify with you that your card wasn't stolen. (This happened to me in the middle of Christmas Shopping last year). In addition to the fee's, many non-bank ATM's have a limit you can get from their machine as well (usually $300-500).
If carrying a lot of cash makes you leary, and you don't want to charge. Then definetly get the traveler's checks.
When we carry large amounts of cash, we break it up between people. So no single person has all the money. Also, I carry a bag with my wallett in it. It has 2 straps that attach to my wallett in different areas and we put it in the middle of the bag between everything. A pain if you want the wallett really quick. However, it makes sure it doesn't fall out at Disney accidentially, and if someone wanted to "pick-pocket" our wallett. They'd have to go through alot of items in the back pack along with unlatching 2 separate hooks, I feel pretty sure (our bags are packed tight) that I'd feel them.