Educated southerners are actually very easy to understand, because they don't speak quickly and they tend to be pretty smooth (I'm speaking of Mississippians in particular). I learned this when I was courting my wife (TN born and raised by two MS parents), and we sent recordings to each other. I'm from the Pacific Northwest, and I was surprised at how fast and clipped my speech sounded when I listened to a recording of myself - it was a lot different than how I sound in my head.
Of course, country southern is a whole other ball of wax.
Best similarity I can think of from across the pond is my limited exposure to lowland vs. highland Scots. Lowland sounded more mellow and smooth to me, highland was all **** and balls.
You guys might have trouble understanding me speaking if you ever talked to me. I can get carried away.