Hello! I know Italy VERY well and have worked in Rome for 7 summers and am returning again this July and am always curious for some great day trips. Have been to Sperlonga, BagnoCivita, Tivoli/Adriana,Orvieto, Viterbo, Orto, Pompei, Naples, Sorrento, north like Florence,etc. But if anyone knows some lesser known spots,just for a day, I would REALLY appreciate it! Grazie mille!
We really enjoyed the Etruscan necropolis in Cerveteri. No crowds; in fact, very few people at all, which is a nice change of pace. Follow that up with a visit to the Etruscan museum back in Rome.
Frommer's has info: http://www.frommers.com/destinations/print-narrative.cfm?destID=64&catID=0064020291
how about Assisi?
You might need a car to get there but have you considered the Abbey of San Galgano? It's a deconsecrated abbey that has gone to ruin, with the roof completely gone and the interior all grass. My Italian instructor said Italians love to go there as a get-away. It's supposed to be absolutely beautiful. Google it for some pics and/or go to this website:
Palestrina
Zagarolo
You take the blue bus from the metro stop before Rebibbia (which in this moment escapes me) to go to Palestrina.
The train runs to Zagarolo.
Another beach spot would be Sabaudia.
Try Anzio - an easy day trip from Rome. Nice town and a good beach.