We also live in the Raleigh area, and we usually drive as well. As a matter of fact, we'll be loading up the minivan in just over three weeks and making the drive once again. In our case it will be my wife and myself, along with our 10 and 6 year-old sons, and our three-year old daughter. I consider it to be about a 10-hour drive with average traffic. With three fairly young children, we do tend to make a number of stops for meals, rest areas, etc., and that does slow things down somewhat (turning that 10 hours into about 12). Our last two drives down have been the last two spring breaks, both of which were adjacent to Easter weekends, and the traffic on I-95 was just horrible. At other times of the year it hasn't seemed so bad.
We have driven it straight through on some trips, and on at least a couple we have elected to break it up by spending the night somewhere along the way. For the upcoming trip, we are staying in Jacksonville on the way, which will leave us with a fairly short drive (about 2-and-a-half hours) the next day.
We have also flown, and with Delta having low-fare, direct-flights from RDU, it is tempting to avoid all that time in a car. But as you know, even with low fares, a bunch of tickets add up quickly, and then you have ground transportation costs in Orlando (shuttle, town car, or rental car). So there is a substantial cost savings in the drive (even at current gas prices

), plus you get the flexibility of having a car on site, and a little more freedom from a packing perspective.
In re-reading your post, I'm not sure if you were looking for suggestions on making the fly vs. drive decision, or on where to stay to split up the trip. Most of the above commentary concerned the former. For the latter: Unless you are leaving much past noon, I would think you would probably want to drive at least as far as Brunswick, GA, to get the majority of the drive behind you. If you are leaving in the morning hours, then I would recommend going to the Jacksonville area which should put you less than three hours from WDW. There are a number of hotel choices in the southern part of Jacksonville just off I-95 (for example, in the area of Bay Meadows Rd. or Butler Drive). I have stayed at several hotels in that area...This has the advantage of allowing you to be quickly out of Jacksonville the next morning.