I know lots been said here about Roma Pass. Roninrome has the most complete description. We just left Rome and felt it to be the best bargain in Italy, probably the only given the dollar keeps sliding. We didn't expect to ride the Metro but found it so useful to save time. Also we skipped the long ticket lines at the Colosseum.
Thank you Julie. We just bought the ROMA PASS. We felt that it was a good deal as long as you used it, which we intend to do!
Just a tip, if you use the Roma Pass for the Borghese Gallery, you must call for your reservations rather than booking online. We made the mistake of booking our reservations online before arriving so we weren't able to use the Roma pass for our admission to the Borghese. Also, we thought that the catacombs would accept the Roma Pass but they didn't. Have fun!