Numerous airlines have direct flights to the major airports of Italy. The national carrier of Italy, Alitalia has daily flights into Italy from around the globe. Rome & Milan are the principal airports for intercontinental flights arriving into Italy. Most people choose to arrive in Rome and depart from Milan, touring the three principal cities of Rome, Florence & Venice in-between flights.
Florence does not have an international airport, but Venice airport has a daily non-stop connection with New York on Delta. Others may arrive in Italy by air from another European country. If you are visiting Italy as part of a European tour you might consider utilizing a low-cost airline to travel between countries.
Airlines like Easyjet and RyanAir offer great value in airfares, as well as the opportunity of booking one-way tickets through which you can build a nice itinerary through the major destinations of Europe. It seems that each European country has a host of these low-cost airlines so shop around for the best deal.
For North Americans visiting Europe via the UK, book your transatlantic flight into London, with the number of airlines flying into London the prices are usually low, and then book your onward travel via low-cost airlines. This method can result in huge savings when compared to booking flights from the US directly to Italy & Greece in particular.
Another popular way of arriving in Italy is by train using Eurail passes. Travelling by train you'll get to see a lot of the Italian countryside, perhaps arriving via the Alps into Venice or Milan. Always try to reserve Euro-star trains where you can make seat reservations and be guaranteed to travel on the most comfortable trains. Beware of night trains within Italy as the local TV programs and Newspapers have featured many nightmare stories of passengers sleeping in insect infested cabins.
Along with the low-cost airlines, you'll also find a wide selection of low-cost bus companies operating services from numerous European countries into many various Italian cities. In fact, most tourists arrive in Italy by bus, and if you are a single-traveller and young or young at heart you'll find many companies that will offer basic, but good value services including overnight buses to save on accommodation costs. Many of these bus companies have pre-arranged deals with local campsites or hostels through which you can enjoy further savings once you arrive at your destination.
If you plan to arrive in Italy by car you'll find it's easy to travel through the Italian peninsula via the Autostrada's (toll-highways). A typical toll-fee from Venice to Rome would be around 60€, and unfortunately the petrol/gas prices in Italy are on the highest on mainland Europe - around 5.50 US a Gallon. Once off the major routes you'll find navigating Italy a little difficult, the Italian drivers won't give you time to think and many city centres are now very confusing because of the complex system of one-way streets.
Also, note that travel in July & August can be chaotic, as during this time around 16 million Italians take their annual vacation. Italy is also going through many different changes in regards to the use of motorized vehicles. Many cities like Florence have banned vehicles from the city centre. If you are only visiting a city for a day, try to park on the outskirts and take public transportation in the city to avoid heavy parking fees and losing your patience.