Combine broccoli and cauliflower in a large bowl. In a separate bowl, combine the mayonnaise, sour cream, sugar, poppy seed, salt and pepper to make a creamy dressing. Add the dressing to the broccoli–cauliflower mix, stir/toss to evenly coat the vegetables. Stir in the bacon and the cheese. Chill in refrigerator for 3 - 4 hours .. Stir before serving.