For an absolute classic, replace the tea syrup and seltzer with 1/2 cup cola.
Bring sugar and 1/2 cup water to a simmer in a pot, stirring until sugar is dissolved. Remove from heat; add tea bags and let steep 10 minutes. Remove and discard bags; let cool completely. Refrigerate 1 hour or up to 1 week.
For each cocktail, fill a tall glass with ice. Add 2 ounces tea syrup, the alcohols, lemon juice and seltzer. Stir. Garnish with a lemon round; serve immediately.