Italy is a country made for meandering, but visitors often find themselves tripping over incidentals, such as admission fees, public transportation costs, and coperte (service charges at restaurants).
One trick to cut costs is to buy "city cards" from the City of Rome. The combination passes offer free and discounted entry into museums, events, and public transportation.
The Roma Pass €20 is valid for three consecutive days. It includes free entry for the first two museums/sites, plus discounted entry for a selected list of museums, sites, and events. Obviously, the key to getting the most value from the card is to visit the most expensive two places first, such as the coveted Galleria Borghese. In addition, the pass includes a three-day transportation pass for unlimited entry on all buses, trams, metros, and some regional trains (excluding the airport train).
The Roma&Più Pass (or "Rome Plus" Pass) €25, includes the above features, but it expands the museum and transportation network to more regional sites, trains, and Co Tral regional buses. It's best if you plan to take excursions far out of Rome.
Roma and Roma&Più passes are available at all museums and sites included in the Pass, at the Tourist Information Points (Punti Informativi Turistici, PIT) around the city or online at romapass.it.
Roma Archaeologia Card €22 is best for Ancient Rome buffs. It acts as a seven-day, free entry pass to the Colosseum, the Palatine Hill, and the Roman Forum, the Palazzo Altemps (famous for its statues), the Palazzo Massimo (famous for its frescos), the Crypta Balbi (a rare explanation of Roman life in the early Middle Ages), the Baths of Diocletian, the Baths of Caracalla, the tomb of Cecilia Metella (via the famous stone road out of Rome, the Appia Antica), and the Villa of the Quintili.
Unlike the Roma Pass and the Roma&Più pass, Roma Archaeologia Card does not include a multi-day transportation pass. But that doesn’t matter because most of the sites that it covers are within easy walking distance of each other.
A tip: Many of Rome’s museums are closed on Mondays, so take this into account when purchasing the Rome Archaeologia pass. In other words—don’t start on Monday.
Roma Archaeologia Card is available at all the sites it offers admission for, except for Cecilia Metella and Villa of the Quintili, which are outside the city center in the Appia Antica Park.
A note to students: Lately, being an American student in Europe is far less economical than the European counterpart, and not just for the fault of the dropping dollar. Museums, archaeological sites, et. al., offer reduced rates (ridotto) for European students only, proffering a knee-jerk (and wallet-cramp) reaction from most visiting US students.
—Erica Firpo, blogging for us from Rome for our Affordable Europe series.