I'd probably break up the highlights into two half day tours. 1) The Vatican 2) Colosseum, Pantheon, Trevi Fountain, and Spanish Steps. The last time we went to the Vatican we waited in the crazy long line to get into the museum. I haven't done any research, but if there is a way to avoid that by buying special tickets or a private tour, I'd do that. For the Colosseum, etc it may be smart to do a private tour. The sites are sort of spread out. A private tour will get you past the lines at the Colosseum. I may go over to the Trevi Fountain later at night for pictures to avoid or minimize the crowds. In fact, I think I may try to talk
@met19 to go out for night photography just as it's about to pour down rain on us... and then we can run back to the hotel bar... Sounds like fun.
Yeah, I'd really like to do a food tour in Trastevere. I've heard great things about that area.