Once upon a time there was a night train Florence-Paris.

It left Florence (Santa Maria Novella station, in the centre) around 19:00-20:00 and arrived in Paris (Gare de Lyon) if I recall correctly around 9:30 the morning after.

The plane required:

1) being at the Pisa airport (which is a 1:30 hour train/bus away from the center of Florence) 1:30 before departure

2) roughly 1:30 boarding and flight

3) 15-30 minutes to collect luggage (if any)

4) 40-60 minutes from the Charles De Gaulle Airport to the centre of Paris

All in all 5-6 hours total.

Choosing the train (which - depending on the arrangement could also be cheaper, including the dinner, than the plane) was a no brainer for me.