I know I'm not in the traditional "South" as BROOKLINEBIKER was probably asking about, but we are south - Commuting in El Paso, Texas is very nice. Part of the attraction is the anonymous nature of cycling in ELP. Since there's not a huge political cycling "movement" here there is also not a big anti-bicycle backlash. Therefore is is relatively safe. Read my blog on the subject (if you're interested) here: The El Paso Cyclist: Why Bicycling is Safe in El Paso for an explanation.

El Paso is ranked as the safest large city in the country, too. We have nice weather, although hot in the summer. There are some very nice pro-level lbs's as well. I know BROOKLINEBIKER that you're probably not interested in the Desert Southwest, but we are a "southern" city, so I though I'd give my dusty burg a thumbs-up!