Should I buy a rail pass before I go to Italy? I will be going from Venice to Florence, Florence to Rome, Rome to Naples, then back to Rome? Not sure if it's best to get one? Help thanks
No, buy tickets in advance, as far ahead as you can at http://www.trenitalia.com/tcom-en
Or try the other train company: http://www.italotreno.it/en
A pass in Italy is a total waste of money. It's even cheaper to just buy tickets from the counter at the start, but cheapest to buy in advance online.
jones,
A Rail Pass is rarely good value for travel in Italy, as tickets are relatively cheap if purchased in advance. All of the routes you mentioned are served by high speed Freccia or Italo trains, which travel at up to 300 km/h. Also keep in mind that Rail Passes do not include the seat reservations which are compulsory for travel on those trains. You'd need to pay separately "out-of-pocket" for those, or risk hefty fines which will be collected on the spot.
If you buy well in advance, you can get Super Economy or Economy tickets at a discount. These are specific to train, date and departure time, so can only be used on the ONE train listed on the ticket. However note that the cheapest Super Economy tickets are non-refundable and non-changeable once purchased, so choose carefully. The tickets include the compulsory seat reservations.
It's not likely that you'll be taking the slower Regionale trains on those routes, but if you do use those at any point, you MUST validate locally purchased tickets prior to boarding the train on the day of travel or risk hefty fines. The same applies to Metro, Buses, etc.
Check the Trenitalia website to see the solutions on the routes you'll be using. Note that you must know the Italian names of the stations you'll be using (many cities have more than one station). You can buy tickets either from the Trenitalia or Italo websites, or from www.trainline.eu which sells tickets for both networks.