Make it boozy: Add 1 ounce of vodka or gin to each glass before the soda.
For a sweeter drink, use more simple syrup.
Try different juices like grapefruit or pomegranate for variety.
Make a big batch in a pitcher, but add the soda just before serving to keep it fizzy.
Use frozen cranberries as ice cubes to keep the drink cold without watering it down.