I will be spending almost a month in Italy, Rome and Milan including. I decided for such a long vacation because I realized that only a week or two is simply not enough for fully enjoying everything this country and these cities has to offer, So, I decided that extra money for a longer stay I nothing comparing to what I can see and experience in Italy. Anyway, I was thinking of using Trenitalia services, because they showed ok last time I was there.
I think you should know that Trenitalia is excellent for traveling through entire Europe too. And the prices are very affordable. For example, you have Paris with the price of 25 euros which is a bargain, Vienna for 29 euros, Prague for 49 euros etc. This means that if you have the necessary papers within that month you could also visit some other European countries at a very fair price. By the way, I really envy you on your free time and money which gives you opportunity to travel whenever and wherever you want.