Preheat grill to medium-high heat (400°F).
Cut pineapple into ½ inch rings or wedges.
Mix brown sugar, granulated sugar, cinnamon, and salt in small bowl.
Brush pineapple with melted butter on both sides.
Sprinkle cinnamon sugar mixture on both sides. Press gently.
Oil grill grates lightly.
Place pineapple on grill. Do not move for 3 to 4 minutes.
Flip carefully. Grill 3 to 4 minutes on other side.
Done when caramelized with grill marks and golden sugar.
Remove from grill. Transfer to platter.
Serve hot with ice cream, mint, or whipped cream if desired.