travel from Rome to Citavecchia

Sounds like a cruise. You may need to define "easiest" -- how many children, ages, luggage, etc. There is a convenient train that runs about every 20 mins, less than 5 E from the the Rome station. Total time is 45 mins to 1 and 15 depending on which train. The Cit train station is about a half mile from the port and easy flat walk. With kids and lot of luggage a private car for about 150E or more will be the easiest. Not much in between.

the cleanest and easiest way to travel with luggage and children is the prepaid transfer services provided by the cruise lines, with trains you might have to deal with pickpockets etc and you would still
have to get local transport from train station to port!!!! roundtrip

have been there and done it...linda