Flying from any US City to Italy

This is kind of open ended but anything on the east coast would be preferable, so Newark, Dulles, etc where Southwest flies to.

An underrated resource is Wikipedia. If you wiki an airport,they all have an Airlines/Destinations section which tells you which airlines fly nonstop to what destinations. CTRL - F "Rome" or "Milan" or whatever and see what airlines fly there.

ETA:
You are in Houston? You may have a nonstop.

ETA2: Looks like you don't, but that's your preference if you want to connect domestically or connect in Europe after a IAH - Europe flight.

Just go to Alitalia's website and see which cities they fly direct from Rome to the US into. There's probably not many, most go through MIlan. You are going to have to fly either Alitalia or a Domestic Carrier to fly direct into Rome.

OP-since you are changing airlines a few things to be aware of:

1. Southwest will not interline your bags. So you'll have to pick them up at the carousel in whatever US city you're in and head to the ticket counter for the INTL carrier.

2. Neither carrier in either direction will care that your flight was delayed if it causes you to miss the "connection". So if that southwest flight on the outbound is delayed and you miss your Italy flight you're SOL.

i've taken the atl to rome flight on delta. super easy.

We flew American Airlines from CLT to FCO and returned VCE to PHL this past spring. We did not have any problems. There are two different train options to bring you from FCO to downtown Rome. One is direct, Leonardo Express, and the other, Regional FL1, makes a few stops and could be the better option depending on where in the city you are staying LINK. You can buy tickets in the station right before boarding the train. For train travel throughout Italy we booked tickets through ItaliaRail.