Personally i would recommend choosing one of the major cities, Milan, Venice, Rome or Florence. It really depends what you are looking to get out of your trip.
Milan is one of Italy's biggest city's filled with things to see and do. If you want to see the sights you could check out any of the following:-
Milan is one of the major artistic centres of northern Italy. Its chief landmarks include:
The Duomo, the world's largest collection of marble statues with the widely visible golden Madonna statue on top of the spire, la Madunina (little Madonna), the symbol of Milan.
Teatro alla Scala. Milan is also one of the most important centres in the world for Opera lirica, with his famous Teatro alla Scala (La Scala).
The Galleria Vittorio Emanuele II, a large, covered arcade linking the Duomo's piazza with the Teatro alla Scala.
The Castello Sforzesco ( a castle)
The Basilica of Sant'Ambrogio ( one of the most ancient churches in Italy)
The Palaeo-Christian Basilica of San Lorenzo (another stunning church)
The Biblioteca Ambrosiana, containing drawings and notebooks by Leonardo da Vinci among its vast holdings of books, manuscripts, and drawings, and is one of the main repositories of European culture. The city is also the home of the Brera Academy of Fine Arts.
The church of Santa Maria delle Grazie, which houses one of the most famous paintings of Leonardo da Vinci, The Last Supper (L'ultima cena or Il cenacolo).
The church of Santa Maria presso San Satiro, with a famous trompe l'oeil traditionally ascribed to Bramante
The Cimitero Monumentale di Milano.
The Pinacoteca di Brera, Pinacoteca Ambrosiana, Poldi Pezzoli, the Bagatti Valsecchi Museum and the Musei del Castello galleries, which host a great number of pictorial masterpieces
A huge choice of stunning architecture, beautiful parks and fantastic shopping all available in Milan. Not to mention the hundreds of fantastic bars and restaurants.
Venice is of course most famous for the canals running throught the city. Venice is built on one hundred and seventeen small islands, and holds one hundred and fifty canals, connected by an amazing four hundred and nine bridges, of which only three cross the main canal. The area it covers is a mere 458 kilometres. Although the city appears small, it is really quite extensive for its size. Vaporetto (water bus) is most amazing method of getting around Venice; you won’t find too many public transport routes as unforgettable as vaporetto. Get yourself a travel pass to ride the exlusive vaopretto - single tickets don't come cheap, and are less economical if you plan to spend days touring Venice and exploring every nook and cranny.
The classic gondola ride with the opera-warbling operator is pretty touristy and expensive but the traghetto is a commuter gondola that crosses the Grand Canal at strategic points. It's quite a balance test for newbies (definately an experience)
The attractions in Venice include many remarkable structures, such as an impressive array of bronze work, tapestries and paintings from the 5 th to 6 th century, as well as a whole handful of amazing buildings and galleries showcasing the artistic side of Venice.
If you are looking for the upbeat bars and restaurants, you cannot go wrong with the area surrounding Campo di Santa Margarita in San Polo. There you will find an Irish pub, trendy bars that do the limbo, and just plain fun. The area is frequented by students from the University and is buzzing with life during the weekends as market stalls of fish and vegetables open up.
Florence - The cultural and historical impact of Florence (or Firenze ) is overwhelming. Close up, however, the city is one of Italy's most atmospheric and pleasant, retaining a strong resemblance to the small late-medieval centre that contributed so much to the artistic and political development of Europe.
Its striking buildings, formidable galleries and treasure-crammed churches attest to the Florentine love of display. Even long after it had set on the political and economic horizon, Florence upheld its elegant appearance: its skyline, all russet rooftops and lofty domes, is indeed picturesque.
Nearly all of the main sights in Florence lie within the centro storico. However, there is so much classic art that even given the city’s small size, it’s impossible to see it all in a short visit. Go for quality, not quantity and don’t feel as if you have to see it all.
In addition, though the centro storico has more artistic treasures per square metre than any other city in the world, Florence also has many more low-key charms. Take time to read between the lines by visiting its dozens of lesser-known museums, and stopping by its hundreds of historic churches. You could spend days just taking your time exploring its back streets and quieter piazzas, and seeking out local trattorias and bars
Finally,
Rome.
With a mythic history that spans more than two thousand years, Rome offers as many historical and cultural attractions as any place on the planet. As the capital of Italy, it's also a dynamic modern hub blending old and new. Of course, it's not possible to soak up everything in one trip. Like an old oak tree, Rome has many layers: Ancient Rome, Medieval Rome, Christian Rome and Renaissance Rome to name only a few. It's best to concentrate on those areas you most want to see. At some point, however, everyone must visit the famous
Colosseum, the ruins at the
Roman Forum (check out our virtual tour) the daunting Vatican Museums, Raphael's tomb at the Pantheon, the massive St. Peter's Basilica, and the little jewel that is the Galleria Borghese. A word to the wise: bring comfortable walking shoes. Rome is more sprawling than people realize.
If you check out the following link it will give you a list of all of the cities you can visit in Italy.
http://www.destination360.com/europe/italy/italy.php
It will give you a good description of each place, things to do etc. I just chose the 4 most popular cities for tourists.