For the best flavor, allow the sangria to chill in the refrigerator for at least 30 minutes before serving to allow the fruit flavors to meld. Overnight is even better! Adjust the amount of spiced simple syrup to your desired sweetness. Taste and add more as needed. Use a good quality red wine, such as a Rioja or Garnacha, for the most authentic flavor. Feel free to experiment with other fruits, such as apples, pears, or berries, depending on the season. If you don't have sparkling water, you can use club soda or ginger ale for a slightly different flavor profile.