Originally Posted by
ontheway
...I am also going to take the train to Citaviccia and plan to take a taxi to the Ostiense station and board the nonstop train to the port.
To save you money: instead of paying for a taxi to the Ostiense station you could take the Metro B Line whose Cavour stop is very near your hotel, again in the direction of Laurentina, to the Piramide stop (which is linked to Ostiense station). If you had purchased the RomaPass then this cost would already be covered, or if you purchase individual metro tickets the cost is €1 per person.
Here's the link to ATAC's Metro and City Railways Map (you can see the FR5 which you'll take to reach Civitavecchia as well as the 2 metro lines). It's a pdf and would be worthwhile if you saved it to your computer, IMO of course!
http://www.atac.roma.it/files/doc.asp?r=4