I am from the US travelling for 10 day trip to Italy.
I have different credit cards including Starwood Amex, Continental Visa, Delta Amex, citi Premier Elite pass, Sony visa, Costco Amex.
I was told to be very careful reg. the cash I carry at Italy. Which among these CC are the best to use within Italy - to buy theatre/train tickets, restaurants, fast food etc?
Is traveller's check a good option to carry too?
How much should we tip at restaurants?

Anything else I need to know which will make life easy?