1. Light the grill. Rinse the fish; dry the surfaces and cavities thoroughly. Cut shallow incisions in a crisscross pattern, about 1 inch apart, in each side of both fish. Season each fish cavity with 1/8 teaspoon of the salt. Put a rosemary sprig in each cavity or rub with 1/2 teaspoon dried rosemary. Rub the surface of both fish using 2 tablespoons of the oil, the garlic, the chopped fresh or remaining 1 teaspoon dried rosemary, and the remaining 3/4 teaspoon salt. Sprinkle the bread crumbs on both sides of each fish. Drizzle both sides with the remaining tablespoon oil.
2. Put the fish in a grill basket or onto a very clean grill rack. Cook over moderately high heat for 7 minutes. Turn and grill until golden and just done, about 7 minutes longer. Remove the fish carefully so it doesn't stick.
3. Serve the fish on a platter. Run a knife between the flesh and the bones and lift off the fillet. Turn the fish over and repeat. Repeat with the other fish. Pass lemon wedges.
Roasted Whole Snapper: Purchase one three-and-a-half-pound snapper instead of two smaller ones. Prepare the fish in the same manner through Step 1, using one-quarter teaspoon salt and both sprigs or one teaspoon rosemary in the cavity. Heat the oven to 450° instead of lighting the grill. Put the fish on a rack in a roasting pan; cook until just done, about twenty minutes. No need to turn the fish while cooking.
Wine Recommendation: Snapper is a delicate fish, and though grilling adds some stronger flavors, you'll be best off with a fairly neutral but crisp white. Orvieto Classico strikes the perfect balance.