Heat oven to 350º F. In large bowl, mix cereals and pretzels; set aside. In 1-quart saucepan, heat peanut butter and butter to boiling, stirring occasionally. Pour over cereal mixture, stirring until evenly coated. Spread in ungreased 13x9-inch pan. Bake 10 minutes, stirring occasionally. Stir in raisins and banana chips. Spread on paper towels; cool completely. Store in airtight container.