Marci,
The easiest way to obtain cash in Italy (or most other places in Europe) is via an ATM. Note that your travel funds MUST be in a chequing account with a four-number PIN. The exchange rate on cash withdrawals from an ATM is usually charged at the "Interbank rate", which is good.
I'd suggest checking with your Bank regarding fees on cash withdrawals in Europe.
If possible, I'd suggest travelling with a "backup" ATM card, in case any problems arise with your primary card (something which happened to me when I was travelling in France last year). Having one credit card would also be a good idea.
I wouldn't suggest using Traveller's Cheques, as these will be a nuisance to deal with. Many merchants these days won't even accept them, or will charge horrendous rates for cashing them. I agree with Rick on that point, "I've cashed my last Traveller's Cheque".
Good luck and happy travels!