Line a 13x9x2-inch baking pan with foil, extending the foil over edges of pan. Butter foil; set pan aside.
In a large microwave-safe bowl combine marshmallows and the 3 tablespoons butter. Microwave on 100% power (high) for 1 to 2 minutes or until butter is melted. Stir in rice cereal, granola, and snipped tropical fruit.
Transfer mixture to the prepared baking pan. Using a buttered spatula or buttered piece of waxed paper, press mixture very firmly and evenly into pan. Let stand about 1 hour or until set. Using the edges of the foil, lift uncut bars out of pan. Cut into bars.