Driving to Siena is beautiful. However if driving is not an option, you can take the train from Pisa station to Siena then from there you take a shuttle that will leave you outside the old city of Siena. I recommend you have a map prior to going there, as many people get confused as to how to reach it from the bus stop. Once you are there, my advice is to get the OPA si pass, and visit these five attractions. Just keep in mind that the Cathedral of Siena is one of the most beautiful in the world. If you are an art lover, this pass is the best treat. Here is the link to their site: ENTER I do not think it is necessary to book it on advance. I have been there during different times of the year and hours, and so far I was able to get in with no problem. You can take a break and have a cup of coffee/cappuccino with a cavallucci, a typical cookie from Siena, or gelato by the Piazza del Campo. Shopping in Siena is a lot of fun particularly if you are into beautiful paper, fabrics, and leather.  Food in Siena is delicious but then again anywhere you go in Italy you will love the food. Dishes to try in Siena, if you are meat lover, then of course the wild boar, otherwise you can have pasta dish like their famous pappardelle alla senese.