We really like using disney giftcards. FYI, you can use those at DLR, WDW, at Disney Stores, and on disneyshopping.com. The giftcard never expires, so hang onto it if there's a balance.
Also, in CA, the disney dollars can be turned back in for cash.
We like the GCs because we use our debit card, but I do not like having to enter in all the debits from a week! So we either buy one big GC on our first day, from just about any giftshop, or we split it up by days, and buy smaller GCs each day. I also like collecting the giftcards; they are a little free souvenir for me.
Almost every cart takes them now...the balloons and the lightup things they bring out at dusk are about the only places that don't take them anymore (except for the totally non-Disney owned places, of course). You can visit disneygiftcard.com for lots of info.
If you bank with Chase, you'll be glad to know that Chase ATMs are in the parks and DTD. I found that to be really helpful during last year's "divas" trip, when I ran out of cash and I needed to pay for my portion of a meal!
Cash is too scary for me. Oh, with the giftcards, keep the receipt and keep it separate from the card! They can help if you have the receipt and the card has been lost or stolen. But if you keep them together, well, they can't help you at all, then.
The one time we tried to use a credit card, my husband managed to spend twice what I had allotted for spending.

That's not a problem that everyone has, of course.