What is the best and most economical way to get from a Rome hotel to the Civitavecchia port?
The best and most economical way do not always go together well. I think the best way is a driver and limo with champagne - door to door and on your schedule. But I guess that is not what you are really asking. Cheapest way is the train - a commuter run - three to four trains an hour, 45 mins to 1,15, and between 8 and 12 Euro depending on the train. From the front of the station, look right and probably can see you ship. About a half mile walk along the beach to the port entrance and from there a shuttle bus to your ship. How you get to Termini will depend on the location of your hotel. I recommend you stay in the Termini area so you can walk. We have made that run four times. It is easy if you have reasonable luggage.
Frank, Limo and champagne?I like your style!