For syrup, in a saucepan combine grapefruit juice, sugar and cinnamon. Bring to a boil; reduce heat. Simmer, uncovered, for 5 minutes. Discard cinnamon; cool syrup. Cover and chill.
To serve, fill four 8-ounce glasses with ice. Add about 1/3 cup grapefruit juice to each glass. Fill glasses with ginger ale. Stir gently. If desired, garnish with Texas Ruby Red grapefruit peel curls, edible flowers and fresh mint sprigs.