Believe it or not, the best sweet tea I ever had was about 2 years ago in Knoxville, Tn at a Taco Bell "by the mall". We were on vacation; the girl who made it really pushed it and told me she makes excellent sweet tea. So I tried it and it was undoubtedly the best sweet tea!

Other notables: the pub in Beau Rivage (pre Katrina) Casino in Biloxi and McAllisters (Memphis and Winona, Ms (?? somewhere up there))