1. Stir together apple juice and next 2 ingredients, stirring until sugar dissolves.
2. Remove giblets and neck from turkey, and rinse turkey with cold water. Drain cavity well; pat dry. Place turkey in a large roasting pan. Dip cheesecloth in apple juice mixture. Wring dry. Cover turkey with cheesecloth; pour apple juice mixture over cheesecloth, coating completely. Cover and chill 12 to 24 hours, basting occasionally with marinade.
3. Preheat oven to 325°. Remove turkey from pan, discarding cheesecloth and reserving 3 cups marinade. Sprinkle cavity with desired amount of salt; rub into cavity. Sprinkle desired amount of salt and freshly ground pepper on skin; rub into skin. Tie ends of legs together with string; tuck wingtips under.
4. Arrange celery and next 3 ingredients in a single layer in bottom of roasting pan. Place turkey, breast side up, on celery mixture; pour reserved marinade over turkey in pan.
5. Bake at 325° for 3 hours and 15 minutes to 4 hours or until a meat thermometer inserted into thickest portion of thigh registers 165°, basting every 30 minutes with pan juices and shielding with aluminum foil after 2 hours and 30 minutes to prevent excessive browning, if necessary. Remove from oven, and let stand 30 minutes.
6. Transfer turkey to a serving platter, reserving 2 1/2 cups pan drippings. Pour reserved drippings through a fine wire-mesh strainer into a large measuring cup, discarding solids.
7. Melt butter in a saucepan over medium heat; whisk in flour, and cook, whisking constantly, 1 to 2 minutes or until smooth. Gradually add drippings, and bring to a boil. Reduce heat to medium, and simmer, stirring mixture occasionally, 5 minutes or until gravy thickens. Add up to 1/2 cup chicken broth for desired consistency, if desired. Stir in salt and freshly ground pepper to taste. Serve turkey with warm gravy.
*Frozen whole turkey, thawed, may be substituted.