In large bowl, pour boiling water over gelatin; stir about 2 minutes or until gelatin is completely dissolved. Stir in pineapple juice. Refrigerate about 30 minutes or until mixture is syrupy and just beginning to thicken.
Meanwhile, in 13x9-inch (3-quart) glass baking dish, toss cracker crumbs, 1/4 cup sugar, the coconut, pecans and melted butter until well mixed. Reserve 1/2 cup crumb mixture for topping. Press remaining mixture in bottom of dish.
In medium bowl, beat cream cheese, sour cream and 1/4 cup sugar with electric mixer on medium speed until smooth; set aside.
Beat gelatin mixture with electric mixer on low speed until foamy; beat on high speed until light and fluffy (mixture will look like beaten egg whites). Beat in cream cheese mixture just until mixed. Gently stir in pineapple (with juice). Pour into crust-lined dish; smooth top. Sprinkle reserved 1/2 cup crumb mixture over top. Refrigerate about 4 hours or until set. For 18 servings, cut into 6 rows by 3 rows.