Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, about 10 minutes. Drain bacon slices on paper towels until cool enough to handle, then chop into small pieces.
Place bacon in a very large bowl with broccoli, cauliflower, almonds, raisins, Cheddar cheese, red onion, and celery.
Whisk together mayonnaise, sour cream, cream cheese, sugar, and lemon juice in a separate bowl until creamy. Pour over broccoli-cauliflower mixture; stir until well combined. Refrigerate until flavors have melded, at least 30 minutes.