Italy’s rails is quite extensive–but less expensive than most European rails.
The Turin to Venice route in itself passes through many compelling cities, including Milan, Brescia, Verona, and Padua to name a few.
In general, train travel in Italy is less expensive than other countries in Europe. Most seasoned travelers just buy point-to-point rail tickets.
For more detailed information on Italy’s rail system, and to buy tickets, see the Trenitalia site. If you are planning a European trip by train, you might consult the German DB Bahn site.