Combine sugar, water, syrup, and salt in a 3-quart saucepan; cook over low heat, stirring constantly, until sugar dissolves. Cover and cook over medium heat 2 to 3 minutes to wash down sugar crystals from sides of pan. Uncover and cook over high heat, without stirring, until mixture reaches firm ball stage (242°).
Beat egg whites (at room temperature) in a large mixing bowl until stiff peaks form. Add half of hot syrup in a thin, steady stream, beating constantly at high speed of an electric mixer. Cook remaining hot syrup over medium heat, without stirring, until mixture reaches hard ball stage (260°). Gradually pour in a thin, steady stream over egg white mixture, beating constantly at high speed of an electric mixer. Continue beating 5 to 10 minutes or until mixture holds its shape when dropped from a spoon. Stir in walnuts, cherries, and vanilla.
Drop mixture by teaspoonfuls onto waxed paper; cool completely. Store in airtight containers in a cool place.