Realistically, Atlanta is no worse than most metropolitan areas. Try LA at any time, or St Louis, etc. If you want to avoid winding two lanes and major metropolitan areas and stay warm you have very few options. My advise is to pick a route and go. Hundreds, if not thousands, of snowbird RVs transit Atlanta each fall and spring with no, or little, problems. Having been through Atlanta twice a year for 11 years the only problems that we have seen are caused by accident-caused backups and those are a possibility everywhere. Every years there is more traffic and very few additional roads.