We've done this before from Boston... Our kids were 4 & 2... We had a great trip! We stopped overnight at the Sheraton in Richmond VA... we had lots of juice boxes, water, poptarts & cookies (all very good foods LOL)... Our kids really did have a good time... we brought toys & such & also Bear in the Big Blue House music tape.... If you leave Saturday morning, you could be there by late Sunday night with an overnight stop... I wouldn't do it without the overnight stop though....
On the way back, we drove over to Hilton Head Island & stayed at Disney's resort one night & then the next night stayed in Richmond again..... We were on a two week trip... that's worth mentioning.... 2 weeks with that drive is good.. although if you are flying back, 1 week should be okay...
Good luck, it's a nice adventure!!!