Crème de cassis is an essential part of the Kir Royale cocktail. If you want to add different components, then there have been many inventions varying on the original ingredients of the Kir Royale.
Here are some cocktail variations on the classic Kir:
1. Kir Imperial: Champagne with raspberry liqueur.
2. Kir Pêche: White wine with peach liqueur.
3. Kir Breton: Brittany cider with Crème de Cassis.
4. Kir Normandy: Normandy cider with Crème de Cassis.
5. Cardinal: Crème de Cassis but topped with red wine instead of white wine.
As a rule of thumb, variations on the Kir cocktail should not be too sweet, so using a dry wine or champagne is ideal. That said, many of these cocktails can be sweetened by adding more liqueur or sugar.