Sage advice above from some of the RS Travel Forum vets...
If you are not already locked in on the air, first order of business is to book an open jaw flight, into Milan or Venice, out of Rome. And late November you want to travel north to south, in theory you would be heading to warmer weather in Rome. I say fly into Milan because I've found there are many more flights from the States to Milan than Venice. If set on Venice as a destination, it's a 2.5 hour train ride from Milano Centrale to Venezia Santa Lucia station. On the same subject, although overnight flights are the bane of my existence, to Europe it's actually not a bad thing because by arriving in the morning, you have the whole day to get your bearings straight & then by the next morning you're OK jet-lag-wise--at least that's the way it worked for me. Flying home from Rome, you would leave around noon & arrive early evening on the same day.
9 nights--either 2 Venice, 3 Florence, 4 Rome, or skip Venice, still fly into Milan, 90-minute Frescia train ride to Florence, 4 nights there, 90-minute Frescia train, 5 nights Rome. Yes, Pompei from Rome will take an entire day. We toured it from (much-closer) Salerno in March--1 hour each way by train, 4 hours at the ruins, on a nice day. Find a nice day--those stones must be treacherous in the rain! However, Pompei should not be missed if at all possible--it is absolutely fabulous, especially using the RS Pompei podcast because almost nothing is marked. But weather will undoubtedly play a big part in your enjoyment of the ruins.
Enjoy your planning!