1) Don't go there on summer (
too warm).
2) If you want to visit Coliseum, be ready to go there at 6:00 am.
3) Too many homeless people and garbage on the streets (Rome is a very dirty city).
4) Crossing the road is a challenge, because the local drivers have no idea about traffic lights and zebra.
5) Vatican church is a definitely must see place there. The line moves very fast. So it will take not more than 10-15 minutes to get inside. Just make sure your woman has her shoulders covered. Photos and video shootings are allowed.
6) The standard taxi price from da Vinci–Fiumicino airport to anywhere in Rome is 40 euro. Don't pay more! Alternatively you can get a place in shuttle for 25.