Definitely, definitely, go for Italy.

Whether or not you attack another Catholic faction (like the Huns) first so that you can then take Italy without being ex-commed, is up to you. (You know best as to how many men you can risk losing, after all.) Even if you do ex-commed for invading Italy, however, it's still worth the risk. Here are the reasons why:

1.) As has already been pointed out, the Italian provinces will give you some very nice income, particularly Venice. It will also allow you to build up a trade network in the Mediterranean, which will improve your financial woes tremendously.

2.) Owning Italy will allow you to attack the Pope if need be, thus cancelling any excommunication you may be under.

3.) If I'm not completely mistaken, you'll need to take part of Italy anyway to help fulfill your GA goals.

In the end, taking the Italian provinces will allow you to kill 2-3 birds with 1 stone.