Doubts on day trips from Florence

Hi everyone,

We will be visiting Florence next week and we have 3 days for doing day trips to cities/towns nearby. One day we are planning on doing Pisa/Lucca. But we are not sure the other 2 days.

The options are the following: - Bologna - Arezzo - San Gimignano/Siena

Which ones would you recommend for a couple (mid 30s) visiting Italy for the first time?

Also, in the case of San Gimignano/Siena, would it be better to rent a car? I saw that the other options have more direct options by train.

Thanks!