I decided to write a quick summary regarding the Roma Pass features and I hope travellers would benefit from my outline:
1. Only buy the Roma Pass from Tourist Information Offices, NOT from tobacconists and other secondary resellers.
2. Explain to the Tourist Office advisors what are you intending to do, where are you staying and they will give you a very sensible advise if the pass is good value for money" in your situation.
3. The pass is valid 3 calendar days, not 72 hours - as a tobacconist deliberately misled me when I bought mine. That means you are better off purchasing and starting to use early in the morning as it will expire at midnight of the third calendar day.
4. Pass is generally not worth it if you travel with kids or young teenagers:
a. Most attractions are free for people under 18 years of age (including most historical sites such as the Colloseum and Forum Romanum and all)
b. After using the first two free entries ( and that would be generally a value of 12-20 Euro depending which sites you do first), you essentially loose the advantage of the skip the queue as you have to queue and buy tickets before proceeding to the entry. In most places entry queue and ticket queue are combined so you don't skip much of the line.
5. Metro travel is 1.5Euro in each direction - so make a good calculation what are you going to save with a Roma Pass. Likely you will do 6 trips in 3 days - total of 9 Euro from a 34 Euro value.
Overall, Roma Pass is only worth it for adults and in case you are planning very active sightseeing concise in 3 days.
Hope it helps.