Florence is certainly a popular destination. A beautiful city with impressive history, great museums, beautiful churches and many things to keep occupied any visitor. Florence is located almost half way between Rome and Milan and as such is very easy to access it form these cities or many others around the country.
Trains are probably what make more sense to travel to Florence. It is a city that can be explored in a day and there are many trains from the early morning to late afternoon. The important thing is to buy tickets ahead of time directly from the official website of trenitalia -the government company of trains- in this way one can take advantage of better prices. A round trip train ticket can cost as little as 40 Euros per person. We are talking here of the high speed trains that make the trip in one hour and 20 minutes from Rome to Florence.
There are two major train stations in Florence, for tourists its better to buy tickets to Florence Santa Maria Novella since this train station is located right in the center of the city and within walking distance to all tourist attractions. Once one has bought the ticket in the website -it is possible to do so with credit card- one has the opportunity of choosing the seats. Fast speed trains called Freciarosa and Freciargento are very nice trains and the seats very comfortable. There is first and second class, but personally I think second class is great. There is a cafeteria on board for those who want to eat something. Do not forget to print your ticket and present it to the personnel of the company who will be checking it during the trip.