"The Sparkler - a red white and blue cocktail rimmed with Pop Rocks - perfect cocktail recipe for the of July!" Why not just do grenadine, sprite, and some blue curacao? I know that grenadine and sprite can layer.
Think of cold beverages as a decorating opportunity. Chill berry-flavored bottled juices or sodas in metal tubs filled with ice for a creative and refreshing way to sneak in a few extra red, white and blue touches.