Hi Cherie, hopefully some of our experiences can help you out here.
Naples is a sore point for us, we were supposed to have visitted there this year on Sea Princess, but the cruise got cancelled, so it's on the to-do list. Most people go & see Pompeii, but we found some good reports on the web for Ercolano & Vesuvius itself - if you are a good hill walker. Ercolano (AKA Herculaneum) is/was a fishing village which was also destroyed by Vesuvius & only now being uncovered.
For Rome, as you know you dock in Civitavecchia, which is a busy & pleasant town, but not somewhere you want to travel half way around the world to see. There are plenty of trips into Rome, but if you feel comfortable with the idea, there is a regular train service from Civitavecchia into Rome, stopping at the Vatican & centre of Rome.
Livorno serves Pisa & Florence. You need to take a shuttle bus into town if you are doing your own thing, then from them use the local buses & trains to Florence, Pisa, or, Lucca. Again all are good & served by English speaking staff. You will be tempted to do a coach trip to Florence AND Pisa, which is fine for a very brief overview, but it will be just that - VERY brief. Most people say that they wish they had done one OR the other, not both as it can be very tiring, especially in the hot, dry Summer months.
I have loads more info on the PC at home, so will post a fuller reply when I finish work today.
If there is anything in particular that you would like ot know, please feel free to PM us & we'll do our best to help.
Alan ( & Katrina )
Last: Cruise Maritime Magellan Nov 2016
Next: P&O Oceana December 2016
Then: NCL Jade August 2017
Then: P&O Ventura December 2017
Golden, Grand(2), Caribbean, Royal, Sea(4+1 aborted)
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Oceania Nautica, Minerva, Minerva II, Fred.Olsen(8), NCL Jade, =X= Eclipse, HAL Ryndam, Aza.Journey, CMV Magellan