Originally Posted by
kevinsac
I do not think you can combine Sienna and Pisa in one day, especially if trying to navigate all of that by train.
Siena and Pisa are in different directions from Florence, so I would not recommend combining them.
Originally Posted by
buckeyeboy
If you are taking a day trip to Pisa from Florence, I'd suggest considering going to Lucca also.
Pisa and Lucca is a good idea, since they're just a half hour train ride apart.