Place chicken in a large resealable plastic bag.

In a bowl, combine 2 tablespoons of balsamic vinegar, olive oil, minced garlic, 1/2 teaspoon of salt, and pepper.

Pour the mixture over the chicken.

Seal the bag and turn to coat the chicken evenly.

Marinate for 15 minutes.

In another bowl, combine the remaining balsamic vinegar, honey, orange peel, and remaining salt.

Prepare a charcoal grill by arranging preheated coals around a drip pan.

Test for medium heat above the pan.

Remove the chicken from the bag and place it, skin side up, on the rack over the drip pan.

Cover and grill for 25 minutes.

Brush with the honey mixture.

Cover and grill for another 25 minutes, or until an instant-read thermometer registers 170°F.

Continue brushing with the honey mixture until the last five minutes of grilling.

If using a gas grill, preheat it and reduce the heat to medium.

Adjust the heat for indirect cooking and place the chicken, skin side up, on the rack on the unlit side.

Cover and grill as described above.

Meanwhile, toss the grapes with sugar.

Place the grapes on a rack over the coals.

Cover and grill for 2 to 3 minutes, turning once.

Transfer the chicken and grapes to a platter.

Serve with cheese (optional) and honey.