Just chiming in to say...stay in Sorrento. After Rome it will be a welcome calming place.
Easy to get to Pompei from Sorrento. When we visited, we stopped in a travel agency by the train station and signed up for a bus tour of Pompei and Vesuvio. I highly recommend that way. Great tour guide, relaxing ride there.
We used Rick's book for a hotel, can't remember the name, but that was also 3 years ago...might have changed.
If you go in December/Jan, make sure to bring a rain jacket...that is the rainy season for Sorrento.
Also, if you are staying for more than a couple of days...see if you can make it to Ravello. Beautiful town on the top of the hill.
This late in the year, a lot of shops might be closed.