We live in Uniontown and take two days, one long first day, then the second more leisurely day so we have extra time to set up and still get to the parks. To do it in 3 pretty equal days stay in Wytheville, VA KOA (nice slide at the pool), and Point South, SC KOA (very friendly staff). Two days we drive to Point South.
We drive the same route as RVUsa, but take 43 to 68 to 79 to start us out. It takes us 17 hours in our trailer with the four kids. (Yes, we have driven straight through before)
The drive is very good (as noted already watch on US19) and not too bad (or any owrse than anywhere else) traffic and construction wise.
If you come back after a holiday weekend traffic can be very bad up 95 and across 26, so we either leave a day early or stay an extra day to avoid this.