Florence's own airport (FLR) is small; many arrive via Pisa (PSA, ~1 hr by train) or by fast train from Rome/Milan into Santa Maria Novella. The historic center is tiny and pedestrian — walk everywhere; a car is a liability inside the ZTL zone.
FLR Florence Airport (Amerigo Vespucci) — 20 min drive
PSA Pisa International (≈1 hr by train) — 75 min drive