Are the buses that you can take to get from city to city? We were thinking of doing a daytrip to Pompeii since it is close.

In the summer you can take the Marozzi bus but you have more flexibility taking the train. Here is the Marozzi schedule.
http://www.alfonsoamare.it/english/marozzi.htm

Thanks kybourbon, that looks like it will work. Do you know how long the bus ride is?

The schedule says 2 hours 40 minutes from Rome to Pompeii. This bus leaves from Rome Tiburtina station not Termini. I took it from Sorrento to Rome 2 years ago. Keep your ticket receipt as the driver tried to say we didn't pay for everyone at the end of the trip. The cost was about 19E and they have a website but I think they are currenly working on it. www.marozzivt.it You don't have to buy round trip tickets so if you want to catch the 7am bus to Pompeii and then take the train back you can.

You have more departure options if you take the train. You can train from Termini to Naples and then change to the local Circumvesuviana train from Naples to Pompeii. For train schedules and prices from Rome to Naples www.trenitalia.it The Eurostar(ES) prices include seat reservations. The Intercity (IC) prices don't include seat reservations.

Enjoy Rome also has a bus tour that drops you at Pompeii and picks you up but they don't allow much time in Pompeii. http://www.enjoyrome.com/shuttle_tour/pompeii.html

topping