If you plan to spend only 1 day in Florence, i would not do the Uffizzi, as it is quite big and time consuming. I also reccomend hiring a private guide to get the most out of the experience.
For day 2, you can take a train to Pisa. There aren't enough things to see to stay more than half a day. The other half you can do the Uffizzi, a brief wine tour or just spend it relaxing in Florence, exploring the less beaten paths.
If you want to explore the Tuscan countryside in 1 day, i would reccomend a custom countryside tour. The pre-planned full day tours might be tempting, but are usually limited in what you get to do and see, and better if you have more time on your hands. Public transportation may be possible, but i would not reccomend it if you have 1 day.