Top 5: Aperitivo

Gusto
This trifurcated food complex up by the Ara Pacis features all level of Italian-dining – from a takeaway cheese counter to pizza to casual bar to osteria to ristorante.  But if you swing by before dinner the osteria/enoteca location and the bar across the piazza both offer a nice aperitivo, starting at 6pm. Wines by the glass and cocktails run about 10 Euro, so it might behoove you to show up with a few friends and get a bottle from the extensive list. Either way, the aperitivo spread is included: focused on small bites and pizzette at the Enoteca, with more rices and cold pasta salads at Bar Tati al 28.
Enoteca: Via della Frezza, 23
Bar Tati al 28: Piazza Augusto Imperatore, 28

Les Affiches
With no outside seating, and nothing but a modest chalk sign adorning the unimposing exterior, you could easily be forgiven for passing by this bar tucked away from the Piazza Navona crowds on Via di Santa Maria dell’Anima. But come 6 o’clock, the small tables and wooden benches fill up for a tasty and, for lack of a better descriptor, cheap aperitivo. A choice from the extensive, though not terribly innovative, cocktail list or the solid wine menu will set you back 5-6 Euro, while gaining you access to an unlimited spread of pastas, rice dishes, salads, crudite and dips, and, quite often, a large mound of fresh ricotta.
Via di Santa Maria dell’Anima, 52

Nuvolari
This enoteca/restaurant takes over a quiet corner of Borgo Vittorio, a (mostly) pedestrian street that dead-ends at the Vatican. The aperitivo (every night but Sunday), ranges from 6-8 EUR depending on your choice of wine of cocktail, and the spread always includes a solid and balanced selection, including salads, beans, and taralli. If you’re still hungry, the attached restaurant offers a well-priced, seasonal menu of Italian classics.
Via degli Ombrellari, 10

Salotto 42
The see-and-be-seen spot to grab an aperitif before heading to a fashionably late dinner. Drinks aren’t cheap (10 euro for a cocktail), but the setting, right in front of Hadrian’s Temple in Piazza di Pietra, and food (sushi before it runs out), make it worth the price.
Piazza di Pietra

Palombi
Also known as “Oasi della Birra”, this oasis in not-exactly-bereft-of-good-food-options-as-it-were Testaccio, has a lot more going for it than just beer. In addition to the extensive international beer list, the walls are lined with wines for the choosing and the buffet tables groan ‘neath heaping platters of deliciousness. The aperitivo is a bit pricier, usually around 10-12 depending on your drink of choice, but the included buffet features hot pastas, bacon-y potatoes, salads, veggies, and the incredible meat and cheese selection that helps this place make its name outside of aperitivo hours.
Piazza Testaccio, 38