Here in Georgia a lot of people drink "sweet tea" and it is served iced and very sweet. I've been trying to find tea that tastes good over ice, without sweetener. The coconut mango wuyi oolong from Stash was good.
My most favorite black tea for serving iced is Harney & Sons Hot Cinnamon Spice tea. It has a wonderfully sweet taste without adding sugar to the brew. I actually called the company the first time I tried it since it was hard to believe that it wasn't sweetened. It contains three types of cinnamon, orange peel and sweet cloves, but no sugar added. You can find it loose, in sachets or tea bags here.
What type of iced tea are you are drinking this month?