Cut an X on the bottoms of peaches, carefully cutting just through the skin. Fill a large Dutch oven with water; bring to a boil. Immerse peaches for 20 seconds; remove with a slotted spoon, and plunge into ice water. Slip skins off peaches using a paring knife (skin will be very loose). Cut peaches in half; remove pits.
Combine sugar and next 6 ingredi-ents (sugar through orange juice). Brush cut sides of peaches with marinade. Place peaches, cut sides down, on a grill rack coated with cooking spray; cook 10 minutes or until tender, turning and basting once with marinade.