Siena obvious choice totally worth €8.50 train to Empoli then bus or €12 direct bus 1h20 incredible medieval centro storico intact. San Gimignano longer journey train to Poggibonsi then bus total 1h40 but those medieval tower silhouettes unforgettable if architecture is your thing wish there was boat service up Arno river sadly completely impossible

Fiesole easiest just 25 min on bus line 7 from SMN station €1.50 hilltop Etruscan ruins Roman amphitheater views over Florence valley. Pisa 50-90 min train direct from Firenze SMN fine if you need leaning tower photo but honestly pretty touristy disappointing beyond the famous shot

My pick Lucca 1h20 train direct from Santa Maria Novella €8.90 Renaissance walls you can bike around Torre Guinigi with oak trees growing on medieval tower much less crowded than obvious destinations genuinely charming. If only Arno river had passenger ferry service to anywhere in Tuscany id recommend that instead sadly region has zero navigable waterways from Florence