I like this a lot more. The only day trip I would recommend with your limited time would be going to Lucca while you are in Florence. It's a wonderful walled town. (Granted, we haven't been to Orvieto, yet. We keep saying "next trip" but there's always so much in Rome it's hard to get away!) If you day trip out of each city, you won't get much of the city and will still spend too much time on trains.

To each his/her own. I think Orvieto is much more interesting than Lucca, and I can't imagine seeing all that Florence has to offer as a day trip.

The problem for you, mel1ssa, is that you won't know your reactions to any place until you get there. But I think you can also look it as there being no "wrong" choices.

<< Nights 4 to 6 in Rome (either a day trip to Orvietta OR Pompeii) >>

Pompeii would be more interesting to your children than Orvieto. Pompeii has little shade and is a long day trip from Rome. An alternative is Ostia Antica, a ruined town and very close to Rome. It's much shadier and easier going than Pompeii and you get the idea of what a Roman town looked like.

http://www.ostia-antica.org/

I like Ostia Antica, the on site restaurant is not bad, just don't expect a great meal

I like your last itinerary, with one caveat (below). Concur that you may want to stay where you are rather than day-tripping, but good to have day trips in mind.

Given your interests, I would plan to take a day-trip to Naples and Pompeii if possible. We did that on our first Italy trip and it was the beginning of a long love-affair with that part of the world. You'll soon be scheming to return. But as Lady1 says, you may decide just to stay in Rome.

My caveat is returning to Milano the day before an afternoon flight. Milano is a very expensive city without that much to see. Looks like the train from Florence to Milano takes under two hours and runs at least hourly. So why not stay in Florence one more nite and make your day trip to Lucca/Pisa then. Then take a fairly early morning train to Milano.

I usually like to stay overnite if I'm flying first thing in the A.M., but with an afternoon flight, I would not want to "waste" a day and a half in Milano.