Rinse lamb chops and pat dry. Trim off and discard excess surface fat. In a bowl, mix chops with olive oil, rosemary, garlic, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Cover and chill at least 15 minutes or up to 2 hours.
Lay chops and sausages on a barbecue grill over a solid bed of hot coals or high heat on a gas grill (you can hold your hand at grill level only 2 to 3 seconds); close lid on gas grill. Turn chops and sausages as needed until they're browned on both sides, lamb is still pink in center of thickest part (medium-rare; cut to test), 6 to 8 minutes total (or done to your liking), and sausages are no longer pink in the center (cut to test), 10 to 12 minutes total.
Meanwhile, mound spinach leaves on a large rimmed platter. Arrange lamb chops and sausages on spinach and keep warm.
With a slotted spoon, lift Molasses-glazed Nectarines from marinade (reserve marinade) and lay on grill. Turn as needed until quarters are beginning to brown on both sides, about 2 minutes total. Arrange beside meats on platter. Drizzle marinade evenly over nectarines and meats. Add more salt and pepper to taste
Molasses-glazed Nectarines. In a large bowl, combine 1 tablespoon each molasses, sherry vinegar or balsamic vinegar, and firmly packed brown sugar. Rinse, pit, and quarter 5 firm-ripe nectarines (1/2 lb. each). Add to marinade and mix gently. Let stand 15 to 30 minutes.