Vacationlover - are you going through Nashville or Memphis? We live in St. Louis as well, have a townhouse in Seagrove Beach and have tried many different routes. Our favorite is I-55 through Memphis. You get off at 240E, drive about 4 miles to 78 east.
78 east is a great highway...you travel about 250 miles on 78, which has two lanes each direction all the way to Birmingham where you merge onto I-65. Very little traffic, roads are great and it's been faster for us. Not sure where in St. Louis you live, but if you live in South St. Louis County you might just like this route. We used to take the Georgianna route, but after a speeding ticket through that town we pretty much stick to 331. Not a whole lot of difference.