In a large sauce pan, combine the cherries with the sugar, water and citrus zests; bring to a boil. Cover and simmer over low heat for 40 minutes. Pass the mixture through a fine strainer, pressing on the solids; you should have 2 ½ cups of liquid. Let cool.
In a pitcher, combine the gin with the Cointreau, lime juice, cherry syrup and a few dashes of bitters; stir well. Pour into ice-filled glasses and top each drink with sparkling water. Garnish with the lime wheels and fresh cherries.