We drive from Eastern Iowa about 19 hours of driving time taken both kids for babyhood to toddlerhood, the Chik-Fil-A's have the cleanest play places we've found and there's several along the interstate once you get to GA. We like to have one person drop parent and child off then drive to get gas (there are always stations in the same lot or across the street, turn child free, the gas getter come back runs in orders food, then adults eat, return to car, feed a runout child(ren) then they usually get a good long rest after a bit of exercise and full bellies.
Otherwise we stuck to cleaner reststops so we could turn the toddler free to run a bit. I found that bringing a cooler of familar food helped, he hates fast food, even at 3.5 will only eat a plain cheesburger, so we took lots of fresh friut, yogurt, etc. We also try to stick to one really, really long day stopping in Valdosta and then one short day to WDW. They are really car seat fatiguged by the time we get there and making that 2nd day any longer would be torture, and they are really good car riders but they all have their limits.