"Best Commuting City in the South" is a bit of an oxymoron. There are plenty of great cities and areas to ride in the South, but I have yet to see one that is particularly commuter friendly. Some more so than others perhaps, but nothing to compare with places like Portland, OR, Minneapolis, MI, or Madison, WI. That said, things have improved a lot in my city, Raleigh, NC. We have more than 100 miles of bike trails, which used to be a rather disjointed collection of short trails. However, the city has been gradually improving the network so you can actually ride fairly significant distances on very nice MUTs. The Neuse River Trail, which is nearly complete, will be more than 30 miles long when completed later this summer. With connecting trails, you will be able to ride a metric century without hardly riding on any roads at all.

Raleigh's bike trail network is aimed more at recreational riding than commuting. There are still very few bike lanes or paths in areas where people are likely to be commuting, but the city is in the process of adding more. Eg, they recently added an intermittent bike lane along the busiest street on my regular commute route, which happens to be one of the few east-west corridors in the northern suburbs.