Train tickets in Italy..Buy in advance or not?

If you have an itinerary set and plan on using high speed Frecca trains then lock them in ASAP to snare the cheapest fares.
http://www.trenitalia.com/tcom-en

The ONLY reason to buy in advance via the internet (Not RailEurope) is to take advantage of any discounts that may be available. But that locks you into a fixed schedule with with no or very limited change options depending on the class of ticket. Base fare today or next month will always be the same. If the discount tickets are not available, then just buy when you get there. And never buy Regionale train tickets on line. Additional restrictions with no discount.

Fast trains - You are assigned a seat number and you must travel on that train because you bought a specific ticket and class. Getting tickets in advance...you will get a discount. Fast trains are the trains that move you from one city to another far city...such as Milan to Rome or Milan to Venice, etc. They have 1st class and 2nd class....not much difference in either as far as creature comforts.

Regional trains - you should buy a ticket at the train station via the electronic kiosks. Super easy to do...and must MUST, MUST validate your regional ticket in a yellow/black box next to the train tracks. It basically prints a time stamp on them before you board the regional train.

jena,

As the others have mentioned, the only advantage to buying tickets in advance is to take advantage of discounts for the fast trains. Tickets for Regionale trains are best purchased in Italy, either at a Kiosk or staffed ticket window as there are no price breaks for those. As mentioned, you MUST validate locally purchased Regionale tickets prior to boarding the train on the day of travel, or you'll risk hefty fines which will be collected on the spot!

There are three basic classes of tickets for the fast trains - Base, Economy or Super Economy. These can be purchased at up to 120 days from the travel date. The cheapest Super Economy tickets are non-refundable and non-changeable, so it's important to be sure before hitting the "purchase" button. Also note that tickets for the fast trains have compulsory seat reservations that are specific to train, date and departure time and can ONLY be used on the one train listed on the ticket. If you board the wrong train, again you'll face hefty fines!

You can purchase tickets either from the Trenitalialia website, www.capitainetrain.com, www.italiarail.com or from www.italotreno.it if you're travelling on their trains.

I buy them in advance a few months ahead to grab the cheaper price. But, another advantage to buy ahead is so I can decide at home which time I'm leaving in the morning for the next location. Then, I don't need to arrive at the train station and try to use the machines and wait longer for the next train; I already know how far in advance to arrive. To me it's less hassle to buy on-line ahead of time.

On the other hand, if it's a day trip someplace, then I keep it flexible because I don't want to be tied down to a specific day or time.

The yellow validation machines are being replaced with green/white/red ones, near the tracks or in the underground passageways near the stairs to the platforms.

Just need to make a couple of statements very clear ----
Getting tickets in advance...you will get a discount. That is not necessarily true. The number of discount tickets are fixed per train. More are available for off hours and fewer for popular times. Once the discount tickets are gone, they are gone. The Super Economy tickets tend to go very quickly very early. Since you are going next month many of the discount tickets probably are sold. If only Base ticket left, buy when you get there.

Have never saw a black validation box. May exist somewhere but yellow was the old color and being replaced with green/white/red. Just watch the locals. If you see someone stopping in front of a box for moment and sticking something into - that is it. Don't (as someone posted) validate the ticket the day before thinking it will save time. Once the ticket is validated it is only good for five hours. Should you forget, grab a pen and write the date/ time on the tickets. That may help you avoid a fine for not validating the ticket provided the conductor is in a sympathetic mood.