Was in Rome 2 years ago and really enjoyed it.
My recommendations hmm ... the obvious
At this time of the year I'm not sure what the crowds would be like for the vatican .. maybe the first day there you can take a strole nearby it and see if the queues are heavy.
My only recommendations are stear clear of the lads selling the handbags and designer glasses.
We ate like kings most of the time there and a jug of house wine was nearly always good in any of the places I visited. We tried doing the Full meal only once as we found them huge.
I'd recommend not eating at any of the tourist attractions as they can be ridiculously priced.
Thats all I can think of at the moment