If you are in Italy and you have your own way of getting around I really suggest that you take a trip to Tarquinia. Tarquinia is along the coast of Italy, and was one of the major Etruscan cities.
There is a Necropolis there with some of the finest decorated tombs in Tuscany.
If you leave Rome head out towards Sutri (the road isn't an autostrada though) and spend some time looking at the amphitheatre there. It might not be as fancy as the Colosseum but it is one that was hewn out of the tuff. There are some tombs there of a different variety and a church that was converted from a Mithreaum.
As I stated before the tombs in Tarquinia are very finely decorated. They have a few recurring elements. Feasting scenes for example are popular for tombs built when times were good. There are other scences though, one is decorated as if it were a forest. Another, known as the 'hunting and fishing tomb', is decorated in hunting and fishing motifs. There was one tomb that was influenced by Bacchic rites with one picture of a woman being whipped (Etruscan S&M?).
Many of the tombs have a happy/peaceful feel to them. There was one though that was built when the Romans started to increase pressure on the Etruscan cities. It had a family being led into the underworld by an Etruscan spirit of the dead. It seemed out of place and sad.
But it is worth seeing, however you need plenty of time since they close at 2pm. We needed to move on so we only saw the tombs, but there is a museum as well.