In very large bowl, beat butter and peanut butter with an electric mixer on medium to high speed for 30 seconds. Add granulated sugar, brown sugar, baking soda, and baking powder. Beat until combined, scraping side of bowl occasionally. Beat in eggs. Beat in as much of the flour as you can with the mixer. Stir in remaining flour, the rolled oats, coconut, raisins, chocolate pieces, cereal, and walnuts.
Drop dough by rounded teaspoons 2 inches apart on an ungreased cookie sheet. Bake in a 350 degree F oven for 9 to 11 minutes or until edges are golden. Cool on cookie sheet for 1 minute. Transfer to a wire rack; cool. Makes about 5 dozen.