Hey Rhino, make sure not miss Villa Borghese, the chances are you will get sensory overload ( all those magnificent pieces of art per square meter) :)
also having coffee at Piazza di Spagna is a must.
I use to go to Rome often, and I have mixed feelings about this city. Its almost schizophrenic experience, strange beauty with some sort of darkness that creeps up upon your heart after a while - hard to explain.
If you have a chance go to Naples - its approx. 4 h train ride (or less depends which train you catch). I'd always trade Rome for Naples - but that's just me.