We have seen most of Rome and would like to expand things. What are good and reasonable day trips from Rome? Which would be better with a tour?
Orvieto is an excellent day trip, about an hour away by train.
Hadrien's Villa & Tivoli are also popular, though I haven't done it myself.
Naples/Pompeii can be done as a long day trip, or you could try Ostia Antica just south of Rome.
Pompeii might be better with a tour, or if you are interested in wine-tasting, you might enjoy a tour that takes you around part of Tuscany.
Florence is also sort of doable as a day trip, but probably better to just go there and give it the time it deserves.
I would suggest a visit to Subiaco and its monasteries, especially San Benedetto. The monastery is built into the rock overhanging the gorge. Dramatic landscape, wonderful frescos on the walls. It is still in use. We went there by chance and it was one of the highlights of a month long trip. We were driving, and spent the night in town on our way back to Rome (it is about 40 miles away) but saw many buses, including tours, in the parking lot as we were leaving. Subiaco is an attractive small town for lunch or dinner. A visit would allow you to see a stunning part of Italy not everyone does, a little off the well worn tourist path.
RS lists several good day trips from Rome in his Rome book. Well worth buying. We particularly enjoyed Ostia Antica (and it's really easy to get to).
Siena is doable...either via train or bus. They take the same amount of time to get there. You can take the bus close to the Tiburtina train station.
I would definitely visit Orvieto; you can easily get there by train from Rome. You don't need a tour for Orvieto. It's very easy to walk around on your own...however I would take the underground tour when you're there. It's an hour-long tour & it's very interesting. I never made it to Ostia Antica but it's definitely on my list for my next trip to Rome. It's also very easy to access via train & you don't necessarily need a tour there. I heard that Rick Steves is putting together an audio MP3 tour for Ostia which might be of interest. Have a great trip!
Orvieto is a marvelous day trip from Rome. Catch an early train. Purchase your ticket for the funiculare tram that takes you to up to the town. Save your ticket as it also is good for the bus to the top of the town. There are some wonderful ceramic art shops, the Duomo with the fabulous Signorelli frescos, many great restaurants and cafes and of course an icy cold glass of Orvieto wine. Your ticket for the frescoes also gets you into the Duomo museum and several other religious art museums that were very worthwhile.