On all of The Traveling Professor's small group tours to Rome, we make sure our travelers have the Roma Pass. It comes in different forms but in essence, it gives VIP, no-wait-in line admission to at least 2 attractions AND provides unlimited bus/tram/metro transportation. The Traveling Professor highly recommends the purchase of the Roma Pass.
My Top Attractions in Rome
The Colosseum/Forum: ruins of an empire 2,000 years ago, I recommend a professionally guided tour. Your Roma Pass will enable you to bypass the hours-long lines like a rock star.
Borghese Gallery: Save the 20 euro admission fee with the Roma Pass, but you will still need to make a (free) reservation. Personally, I am not a fan of sculpture, but the Bernini's at the Galleria Borghese will blow you away. A must stop while in Rome.
Pantheon: The best things in life are free, and so is the Pantheon. I like it because the interior is the best preserved example of what Rome looked like 2,000 years ago.
Market of Campo di Fiori: Nothing like getting to know the culture of a society by seeing what is sold at the food markets. Also at one end of Campo di Fiori is Il Forno, perhaps the best pizza spot in Rome.
The Vatican: There is the Vatican Museum, the Sistine Chapel and St. Peter's Basilica. Avoid the line, which sometimes seems like a mile long by making a no-wait-in-line reservation here: https://biglietteriamusei.vatican.va/musei/tickets/do?do