Still here in Italy and did the Colosseum, the Forum, and Nero's House yesterday. Couple of tips to consider:
Colosseum - Incredible - but get the Roma pass before you get there. The line was atrocious, but we walked right by it.
Forum - This is by far the most underrated sight in Rome. Never before have ruins brought goosebumps to my skin. Plan on spending several hours (we spent half the day) in here as well as Palatine Hill. Bring Rick's Rome 2008 book and forgo the audio tour. Rick has everything there for you already.
Nero's Golden House - This one was bittersweet. My wife and I love history so we were both really looking forward to this. You MUST have a reservation or they will turn you away at the door. Actually, more to the point, the archeologist that happens to have "Tour Duty" will turn you away as this is a working site. The ENTIRE 35 minute tour is in Italian; the guides do not speak English. Also, the tour only shows you about 1/100th of the actual ruins. Don't get me wrong - it was extremely interesting and I have no regrets doing it. But the reservations websites fail to tell you that the tour is in Italian so it can be a waste of money if you're not really into history.
Kent (or Rick) - maybe that should be mentioned in future editions of Rick's Rome guide? We used www.pierreci.it to book the Nero reservations. Maybe other websites are more informative.
Lesson of the day - pay attention to those around you. As we were leaving the Forum, we decided to sit for a small break. We ended up sitting next to David Caruso (the main character in CSI Miami)! He was vacationing in Rome with his daughter, Greta. It was a pleasant surprise and he was super nice!
More details from the field to follow!