Lots of good routes to take, some already suggested. As for AL or MS road conditions, last time I was through that area, they were good. AL in particular has a long history of good road maintenance (born and reared in Alabama). Here's a route you might also enjoy:
US 78/I22 from Memphis to Tupelo (stop at Elvis's birth place if you're into Elvis memorabilia). US 45 S to US 278/45, then US 278 E to Sulligent AL. AL 17 all the way south to US 45 again (or you could just stay on US 45) toward Mobile. For me, the advantage of AL 17 is the various small towns you'll go through and the architectural history that you'll see along the way (many antebellum homes).
Last time I was through, the early portion, US 78 between Memphis and Holly Springs, I thought was particularly rough. Perhaps it's been worked on since then to reach Interstate standards. Some rolling hills between Holly Springs and Tupelo, not a bad drive at all.