I had some grapefruit laying about, but no soda. Made one with an extra 0.5oz (total 2oz) juice, 0.5oz simple, and topped with sparkling water. in this form also, an absolutely delightfully refreshing tart and bitter long drink.
This was outstanding. A perfect bunch cocktail. Refreshing and not overly alcoholic. Wonderfully balance and not overly sweet as some brunch cocktails. On my favourites.