Combine the sugar, paprika, seasoned salt, chili powder, black pepper, celery salt, onion powder, garlic powder, ground sage, and dry mustard and then set the spice rub aside.
Stir the barbecue sauce and honey together in a small saucepan over low heat. Heat through, stirring occasionally, about 5 minutes. Set the barbecue glaze aside, keeping it warm or at room temperature before using. (If you’re storing it for more than 2 hours, cover and refrigerate. Reheat gently before using).
Pat the ribs dry with paper towels and season generously with spice rub, using about 4-6 tablespoons for each slab of ribs. Grill over indirect heat in a covered grill or smoker for 1 ½ to 2 hours. Turn the ribs once during cooking, about halfway through. The ribs are done when the meat is very tender (insert a paring knife between ribs to determine); they will pull apart fairly easily. About 20 minutes before ribs are done, baste them heavily with the barbecue glaze. If you like your ribs extra sticky, baste again 10 minutes before removing them from the grill.