We stay in Decatur ( outside of Huntsville, AL) at this hotel : http://www.holidayinn.com/hotels/us/en/decatur/dcual/hoteldetail
It's a little off the highway ( about 10 mins), but it's about 1/2 way and the suite rate works very well for us. You may meet other Louisville folks there- we have.
Timing- wise I agree with Justin- it's more like 11-12 ( with very short stops). Expect that it will take longer than that given that it's Spring Break- last trip down we literally ran into people we knew at every gas stop.
Be warned that the 331 route is only a 2 lane in some sections and very heavily trafficked on Saturday with folks heading for their week vacation. We try to hit it either early morning or very late afternoon ( heading south) so we don't get caught in the crush of people trying to make it to their 2:00/3:00 check-in.
Have a fantastic time-Seaside is wonderful!