You'll find most locals consuming their alcohol and atmosphere in a leisurely fashion; for example, beverages like aperitifs and digestifs serve to complement a meal (which often occurs after 8pm anyway), while the phenomenon known as passeggiata is a slow, evening stroll taken to enjoy the sights of Rome. The Italians as a whole aren't known to be brash drinkers, but that doesn't mean that there aren't plenty of adventures to be had across the nightlife spectrum. Also of note are the high number of good-sized Irish pubs across the city; Flann O'Brien's on Via Napoli and the Abbey Theatre in the old town are prime examples.
Since you'll be spending a lot of time east of the Tiber River in downtown Rome to see what the city has to show for its thousands of years of existence, you'll be happy to find that the many piazzas in the area are all good for an outdoor drink or two. Of particular popularity are Piazza Navone (and Via della Pace, which starts at the piazza and heads west toward the Tiber) and Campo De Fiori, a market by day that becomes a hot spot for a late night crowd that includes a pretty even number of travelers and locals. Deserving of mention is Open Baladin, located south of Campo de' Fiori, due to its selection of burgers and one hundred available beers. Our travel advice: stop at any of the cafes found on or near the downtown piazzas and take it easy like the Romans do for at least one evening during your stay.
If you're drawn to the club scene, then there are a few different areas of the city that will pique your interest. Testaccio is directly south of city center and just east of the Tiber, with the majority of its establishments running the circuit around Monte Testaccio. There are a handful of dance clubs (L'Alibi, Radio Londra), as well as a few cocktail lounges and bars that all exist in a small area. You'll find a generally younger crowd both here and in San Lorenzo, which appeals to a largely student clientele with an incredible concentration of bars and pubs that center particularly around Via dei Latini and Via dei Sabelli. Also, you can head a few blocks to the southeast to enjoy some of the best live music around at Circolo degli Artisti or catch a taxi even further east to the Blackout Rock Club on Via Casilina. A last area worth mention where a younger crowd prevails is Ponte Milvio in Rome's northern section. There is an excellent selection of bars here, while the bridge itself has gained a reputation as a romantic place for couples.
Then again, probably the best choice for the sophisticates among us is just across the river from downtown in the neighborhood of Trastavere. The narrow streets and cobblestones create an enticing period feel where the many cafes, bars, and cocktail joints only add to the neighborhood's charm. You'll find everything you need within a few blocks of the Ponte Sisto.
Lastly, the outlying community of Ostia may be your best bet for finding a party during the summer months. Most locals head to this beach-side town to the west (a short train ride), where the dank walls of clubs are traded for the open Mediterranean air. If you'd like to know more about what to do in Rome, take a look at our individual pages or peruse the website for further travel ideas. See you in Rome!