re: Western Kentucky Parkway

Take the parkway route. You will like it so much better than going the Nashville to Louisville route (traffic sucks on the interstate through there). Go north from Memphis and hit the western KY parkway and follow it to Elizabethtown. Now here you can still take I-65 north to Louisville, or you can take the Bluegrass parkway to Lexington (recommended) since you'll miss Louisville traffic and I-64. Once to Lexington you can hit I-75 north to Cincy and go from there.

Note: Bluegrass parkway is 9002 on goole maps. Goes by Bardstown and Versailles.

Way more scenic route also, and far less traffic as already stated.