As a U.S. citizen, what should I expect when I arrive in Rome when it comes to baggage and customs?
First the plus side: Rome's Fiumicino Airport (officially named Leonardo da Vinci) is among Europe's easiest to clear customs-wise if you're a U.S. citizen. Remember to get into the NON-E.U. or ALL PASSPORTS line for obvious reasons. Generally speaking it's not a difficult line to negotiate — unless, that is, a flight from Nigeria or Morocco or some similarly "dubious" destination (in Italian eyes) touched down just before you (or a full flight from Beijing, since Chinese tourism is on the upswing). If that happens you're in for a long wait in cordoned-off lines that can run 10 rows deep. But Asian and African flights don't tend to land in the early morning hours, which are the bread and butter of American arrivals.
Customs agents are in numbered booths, much like American entry points, with an agent at the front of the line directing traffic. Since Italy and the U.S. are on cordial terms, you're unlikely to get the kind of third-degree commonplace when entering the U.S. or the UK. Italy survives on tourism, with American visitors an essential part of the formula.
Baggage claim is very much the minus side. Expect to wait between 30 to 90 minutes. Sometimes the carousel moves but remains empty for an eternity (still showing bags from previous flights). So-called "priority" or business class passengers do not fare much better. However, once you do get your checked bags there's rarely any further hindrance. Head for the green "nothing to declare" side and you're on your way.
Some days are worse than other. Customs malfunctions (backups, disorganization, low personnel) and baggage handler snarls (strikes or slowdowns) can be exasperating, and no app will give you the lowdown.
But the lack of vetting that has become the TSA-normal in the U.S. can make some arrivals a breeze. If you have only carry-on, you're basically home free. Remember that these remarks apply to incoming flights from the U.S., most of which touch down between 6:30 and 8:30 a.m. Arrivals later in the morning or in the afternoon are another story as lines and waits grow.