We were in WDW for two weeks last year, staying on site. I used my FairFx pre-paid dollars card (good exchange rates, no fees, can top up while there if you have the app or online access). Left my credit card details at check in just in case, but paid it off a couple of times before checking out with the FairFx card so the credit card wasn't touched. (I don't leave the FairFx card details in case of 'ring fencing'). Using the card or magic bands for charging or tipping was so easy.
Other than that, I took $50 in cash! A lot less than some of you. But it was plenty for tipping the DME driver, and mousekeeping, which is all we needed it for. ($3 per day for 3 of us in the room for mousekeeping, and $1 per case per trip for DME driver = $48) I got it all as single dollars, so no need to panic about not having change.
If we had needed more cash, I could have used my FairFx card at the ATMs in the resort lobby for a small fee (I think it's around $2 per withdrawal but it's a while since I used it at an ATM)