Okay - the rail passes just have me confused. If I have a 1st class rail pass, can I just get on the Leonardo Express? Or do I have do have some other type ticket in addition to the pass?
Yes, but it counts as day so unless you are traveling beyond Termini it is not worth it to use it just for the Leonard Express.
Thanks for the info. I fly in/out of Rome - but will be spending the first few days in Naples, so I will fly into FCO, then take the train to Naples, all on the same day - so that will work!