Add first 3 ingredients and 1/2 cup ginger ale to food processor bowl; puree until smooth. Cover and chill.
Pour raspberry mixture through a fine wire-mesh strainer into a small bowl. Use a rubber spatula against sides of strainer to extract juice; discard seeds. Cover and chill.
Place peaches, yogurt, and grape juice concentrate in food processor bowl; puree until smooth. Cover and chill 1 hour.
Add remaining 1 1/4 cups ginger ale to peach mixture just before serving, stirring well. To serve, ladle about 1 cup peach mixture into each of 5 individual serving bowls; drizzle each with 1/4 cup raspberry coulis. Serve immediately.