If your going to take a cash stash, take smaller denominations, $10's and $20 bills. The US $100 bill is the most counterfeited bill in the world. Especially in some areas of south and central America. Even in Europe the banks were reluctant to accept them unless you had or were setting up an account at their bank.
I use a Bank of America debit card for withdrawing ATM cash for local currency and back it up with an American Express and Capital One credit card. I haven't checked it out yet, but B of A has a travel card that is supposed to have some advantages for travelers?? I don't particularly like B of A, but they do have an abundance of branches and European partner banks that you can use while traveling.
Why three cards? Debit cards are the best deal for ATM's, but have a habit of not always working at some banks and ATM's in countries where debit cards are not used. Don't carry all the cards in the same place, one in your wallet, one hidden somewhere not on your person and I use a money belt for passport and the 3rd card.
Occasionally a card may stop working or be locked out by Visa / Mastercard. I rented a car in Portugal using a VISA card. Tried to use the same card to purchase gas and it was declined. Found out after I got back that the car rental company had put a limit hold on the card to cover the insurance deductible on their car. Once the car was returned, the card started working again.
Notify your card company security that you will be traveling outside of your country and make sure they have your cell phone and email address to contact you. Many companies allow you to do it on line and it's pretty simple. If you don't, they will see out of country purchases and if it's not in your pattern of card use, they may lock down your card until they can contact you.