Welcome to FT!!

The best way to search for availability to Italy is to call United and have them search availability on Star Alliance partner airlines (Lufthansa, Austrian, Swiss, Turkish, SAS). Lufthansa will usually have something across the pond but will require a connection in Germany. If you're flexible you will have a better opportunity of finding a seat.

Also, the ANA tool (if you sign up for a ANA frequent flyer account, the ANA website will allow you to see availability for most Star Alliance carriers on their website) is a very good source of information. Unfortunately, occassionally you will see a flight available on the ANA tool that UA does not make available. It's frustrating but it happens.

I will let other FT;'ers chime in on SWU's.