The carbs; 60lbs of pasta are consumed per person per year, apparently. Eat, pray, love, baby. The Coliseum - check another Seventh Wonder off the list. Those die-hard Twilight fans who descend on the Vatican, jokes. Police who ball hard in Lamborghinis. Outdoor drinking – find a piazza, grab a beer/glass of wine from an enoteca and enjoy.
Tourists get hustled hard. It's too hot in August and everything is shut. The best way to explore is on foot - all the best things are hidden down backstreets. Trastevere is the established drinking hot spot, but there are cooler, more underground things happening in Monti or the up-and-coming Ostiense. Aperitivo hour (cocktails and free nibbles) is a must, daily.