In a large bowl toss together the cereals, melted stick of butter, vanilla and 1-2 teaspoons of the remaining cinnamon sugar from earlier. Toss well and then spread out between two cookie sheets. Bake for 15 minutes at 300ºF, stirring once or twice during cooking. Remove and allow to cool. Once cool, add the cereal, snickerdoodles and pecans to a large bowl and toss well. Serve.