Place chicken in large resealable plastic bag. In bowl combine 2 tablespoons vinegar, oil, garlic, 1/2 teaspoon of salt, and pepper; pour over chicken. Seal bag; turn bag to coat chicken. Marinate 15 minutes.
Meanwhile, in another bowl stir together remaining vinegar, honey, orange peel, and remaining salt.
For charcoal grill, arrange preheated coals around drip pan. Test for medium heat above pan. Remove chicken from bag; place, skin side up, on rack over drip pan. Cover; grill 25 minutes. Brush with honey mixture. Cover and grill 25 minutes more or until instand-read thermometer registers 170°F Brush with honey mixture until last five minutes of grilling. (For gas grill, preheat grill. Reduce heat to medium. Adjust heat for indirect cooking. Place chicken, skin side up, on rack on unlit side. Cover; grill as above.).
Meanwhile, toss grapes with sugar; place on rack over coals. Cover; grill 2 to 3 minutes, turning once. Transfer chicken and grapes to platter. Serve with cheese (or don't) and grapes and honey.