For Florence, look at BLQ (Bologna) or PSA (Pisa) as both are very easy transfers to trains. Neither have TATL service (BLQ had AA from PHL as seasonal a few years ago but I doubt that'll return in the near future). If you want to TATL to Italy, it's MXP or FCO and seasonal to VCE, sometimes NAP and PMO.

If you want to fly to FLR (or PSA or BLQ) you'll have to connect either UK or EU.