1. Combine first 4 ingredients, stirring to combine. Stir in 1/4 teaspoon salt and pepper. Place yogurt mixture in a heavy-duty zip-top plastic bag. Add chicken to bag; seal. Marinate in refrigerator for 2 hours, turning occasionally.
2. Prepare grill to medium-high heat.
3. Remove chicken from bag; discard marinade. Place chicken, breast side down, on grill rack coated with cooking spray; grill 10 minutes or until browned. Turn chicken over; grill 20 minutes or until a thermometer inserted in the meaty part of breast registers 160°. Remove chicken from grill; let stand 10 minutes. Remove meat from bones; discard bones. Coarsely chop chicken and place in a medium bowl. Sprinkle chicken with remaining 1/2 teaspoon salt.
4. Add grapes and remaining ingredients to chicken mixture; toss gently to combine. Chill 30 minutes.
Wine note: With just a bit of heat from the ground red pepper and sweet-tart mango chutney, Grilled Chicken Salad matches perfectly with a glass of chilled Hogue Riesling 2007 ($9) from Washington. The tropical fruit and pear flavors nicely echo the chutney, while the wine's refreshing sweetness and fresh acidity add zip and textural contrast to the creamy consistency of chicken salad. —Jeffery Lindenmuth