In a large mixing bowl, combine the rice cereal, oats, raisins, sunflower seeds, pumpkin seeds and brown sugar; set aside. In a microwave safe bowl, add the honey and microwave 2 minutes. Mix in peanut butter and vanilla, and then microwave an additional minute. Pour the honey mixture over the dry ingredients and combine using a spatula. After ingredients are well-mixed, press into a greased 9 x 13-inch pan. Refrigerate until cool and firm. Makes 24 bars.