We are 2 hours north of Toronto. We drive down every winter. With kids to St.Augustine, our first shopping stop, takes us 23 hours, nobody can co-ordinate bathroom stops.

. Without kids, 21 hours. We have done both routes to Florida. Our favorite, and the one we are taking in two weeks, is the I95 route.
If you are going in the summer, I would take the I95 route. It is very scenic, especially in the summer months. You would have no weather related problems.
We go 400-407-QEW and cross at Fort Erie then 90-79-19-77-95-4. We drive straight through.