Does anyone recommend exchanging dollars for Euros before leaving the US? Or is it a waste of time and can be just as easily done when arriving in Italy?
You'll be fine getting euro at an airport ATM when you arrive in Italy. Be sure to notify your debit card and credit card providers when you will be in Europe or a computer may block your cards for unusual--and therefore possibly fraudulent--use.
Read this helpful article by Rick Steves.
We visited an AMEX office here in the states and got out $200 worth of Euros before departing. With the jet lag and challenge of just finding your luggage, hotel, etc. we did not want to also try to exchange money the first day upon arrival. When you do find an ATM to use in Europe, be careful of nearby panhandlers. We had one approach us after getting money and follow us. We finally turned a corner and quickly ducked into a store to lose him.
I have never failed to find an ATM at any airport or train station on arrival in a country. If you don't see one, just ask. Sometimes I've found one in the arrivals hall, while waiting for my luggage.
Buying foreign currency in the US is not so much a waste of time as a waste of money - the exchange rates are almost always lousy.
If you have enough time before your departure, shop around for a low-fee or no-fee ATM card. Even paying $5/transaction is probably going to be better than the exchange rates at the change places, and you don't have the worry of carrying large amounts of cash with you.
I also recommend the Capital One credit card - no fees on foreign transactions, and so far, it's worked fine for me all over the world.
The exchange rate here is awful, so if you do exchange some for "just in case," do the minimum. I exchanged $100 before we left, did the math, and could've had an extra ten bucks worth at Italian rates of exchange. That's a few gelati!
It's a question of comfort level. Some people prefer to have cash in hand before leaving so they don't have to worry about finding an ATM or the possibility of a problem using their ATM card. But it's definitely true that you won't get as good an exchange rate if you buy euros here before you leave. We've never had any problem getting cash from ATMs once we arrive.
To cover the chance, however slight, that no airport ATM will accept your card, put around $200 in your money belt to use in an emergency. Use some of it to get a few euro from an airport exchange bureau.