Hi, we're in Greensboro and have made the drive lots of times, both with and without kids. From Raleigh, I would estimate it will be between a 10-11 hour drive (we do it in 9-10 hours from here).
We try to leave no later than 7:00 a.m. on a weekend. If you are traveling during the week however, I would recommend you leave at a time that will have you arriving in Charlotte either before or after rush hour....if you get caught up in that it will cost you at least an hour to an hour and a half. Leaving early in the morning also means that you get to Orlando quicker and can have a restful night at your hotel so that you are fresh in the morning.
We find that the quickest route is to take 85 S to Charlotte, then pick up 77S to Columbia. In Columbia pick up 20 towards Savannah, then pick up 95S and stay on that all the way to 4 and take that into Orlando.
We find that if we keep a steady stream of DVD's on, then the kids are very content.