I'm planning to return car in Siena hertz and then take a bus / train back to Rome termini station. What is the best way to go back to Rome? Is it by bus or train and which website is good for making the bookings?
I think the best way for travelling from Siena to Rome is by bus. Actually, train is usually faster, but because Siena isn't well connected to the most important train stations in Italy, you need to go first to Firenze Santa Maria Novella or to Chiusi-Chianciano Terme, and then take a train to Rome Termini, and that takes you more than 3 hours (almost 4 to be honest, with the Firenze option). Moreover, it is not even more convenient: ticket price may vary from 28.00 to 51.70 euro... If you want to have a look anyway, this is the website: http://www.trenitalia.com/ (English version on the right top of the page).
So in this case bus is faster.... there are several direct journeys leaving from Siena and arriving at Rome Tiburtina bus station. It takes less than 3 hours (so even faster than the train trip) and costs 24.00 euros. There are also low cost fares at 15.00 euros, you only need to check availability and conditions of reservations (you must reserve at least 10 days in advance). Here is the website where you may see fare coasts and timetables: http://www.sena.it/Home/78-1-en.html
im just reading your post, i have same question too.
im thinking to stay in florence for 1 nights, and then next day rent car to up until san gimignano bcoz i want to exprience the farmhouse and the view. then next day i tot i can drive to Siena and drop the car in there and take train to Rome.
but as you suggested , for train - we must take it from firenze ?
so is it better if drop the car back to firenze ?
if taking the bus , is it got enough space to put luggage and wheelchair ?