When my husband and I drove, we had 3 kids, and left Massachusetts around 4pm. Stopped around 8:30, got kids dressed for bed, got them all comfy in their carseats, they slept through the night, up at about 6:30am. DH and I switch on and off. This is when we drove to "just north of Tampa".
We got to our destination around 3:30pm the next day. Kids had blankets, pillows, dvd players, headphones, we had a small cooler for drinks, a beach bag of clothes, a bag of snacks lots of them, a trash bag for trash, lots of wipes.
The next time, I drove to Florida by myself first with 4 kids in 2008 then with 5 kids, last June. Obviously with me being the only driver, we had to stop. We left around 7am, got to just south of Dunn, NC around 6:30pm. Got a hotel, ate dinner and swam a bit. In bed by 9pm, up and out of there after the continental breakfast by 7am. Made to "just north of tampa" around 7pm. Obviously me just driving we stopped a lot, and hit some pretty bad rain storms, so slow driving too. Same deal with snacks, cooler, beach bag of clothes, dvd's, kindles, headphones, laptops, ipods etc.
On the way home, made it to Virginia and once I stopped off in DC for a bit of site seeing on our 2008 trip.