I'm not sure about the US money there... I doubt they'll be happy to see that, unless you're in a big hotel, and then they'll get you with the exchange rate.
I've always used ATMs for all my trips abroad. Best thing... ever! Allows me to not carry a huge pile of cash, which if anything happens, would be sad to see it go! With ATMs all over, I always have the minimum I need and the possibility to get more easily.
Beware of pickpockets. they are abondant in Italy, especially in big cities. Countryside is safe, but walking the street of a busy city, zip down, velcro and lock your pockets! I know of a tour guide who got his camera stolen... from around his neck! He didn't realise it until too late... that thief was already far away.
If you can,
Cinque Terre is a VERY popular and beautiful place to visit.
Locals will look like they have no patience and quick to get angry, don't worry, it's in the blood, it's the way they deal with things... they mean well, it's just the way it comes across sometimes, viewed from the eyes of someone from the new continent.
Enjoy the architecture, the pasta and the wine! Cheap and great!
Oh, and be careful! The travelling bug is easily caught, and it might mean that you'll need to go on plenty more trips, should you enjoy yourself on this one!
