Here is the listing of current AZ ST E+ lounges at FCO:

Bramante Terminal 1, departure area (before security)
Giotto Boarding area G
Borromini Boarding area D
Canova Terminal 3, departure area (before security)
Le Navi Boarding area H

It depends what services you deem important. Lounges tend to be quiet, lots of seating...but food options are just ok. Wi-Fi is passable, but one has to navigate thru the AZ red tape...don't expect the lounge dragons to assist you in this matter.

It's better to be in the lounge than general boarding area, that's for sure, but FCO's options are just adequate.

Since you're flying intercontinental, I would suggest the Giotto lounge in the "G" boarding area. It can crowd up during busy AM departures times to the US.