Some vendor carts will let you use your room key charge and some won't. Balloon vendors take cash only. We had no problem using the room key charge at any counter service restaurant except the Rainforest Cafe at AK. They do take it, but the computer system was down. They had to do it manually and then it appeared twice on the bill, but that was fixed at checkout with no major drama. Each day, I carried $100 in case and the room key card. This way, I never needed to run to the ATM. I brought the cash from home, so the remainder stayed back in the room in the safe. We never needed more than $60 a day in cash, but I always like to keep a little back-up. Mickey