I'm going to be in Columbus, MS and possibly Demopolis, AL next week for work, and I'm taking my break-away bike. On the off-chance, I'm writing in to see if there's anybody who knows of some good roads to get my training rides in in those areas.
Thanks,
Chris

You might try these guys - http://www.druidcity.org/

I can't imagine what you'd be in Demopolis for, but there should be lots of pretty flat roads with moderate hills around there. In fact, that's not too far from where the AL State Time Trial Championships were held last month (in Sprott). An out and back 40km with [IIRC] 26 total feet of elevation change. I've ridden a few times around Marion, not too far away, and the roads were pretty low traffic on a Saturday.

There's an organized century, the http://www.samford.edu/oldhoward/index.html#route that begins and ends in Marion. I haven't ridden this one, but at least you'd be on paved roads and there should be some good visible pavement markings to direct you along the way.