I think that you would be safe anywhere around <a href="www.nashvillemastermovers.com">Nashville</a> as far as the mixed race goes. There is a lot of diversity here. East of Nashville is very beautiful and a little more affordable than going South of Nashville so you may end up with more land and a bigger house for the same price. When you get ready to move give us a call, I would be happy to answer any questions about areas, schools, etc!
The mixed-race thing will be less of an issue than you probably think. My neighbors are mixed race (in a town that is 97% white) and there are no issues. People around here are more interested in how people act than how they look. There are far more race issues in the Midwest than in the South. And, Memphis is nothing like the rest of the state. If we could get rid of it, we would - it skews the statistics too much.
You can find a lot of nice farm areas and large lots in both Cheatham and Robertson counties. Both have a low cost of living and are within 30 minutes of downtown Nashville. Cheatham is going to be a little more hilly as far as terrain goes. I would not go SE of town (towards Murfreesboro) or south of town (towards Brentwood/Franklin) as those areas are just growing too fast. You'll feel squeezed in no time. Dickson County is a little further out, but it would also offer what you want.