Cook bacon in a large skillet over medium-high heat 10 to 12 minutes or until crisp; remove bacon, and drain on paper towels. Crumble bacon.
Cook broccoli and cauliflower in boiling salted water to cover 2 minutes or until crisp-tender; drain. Plunge into ice water to stop the cooking process; drain well. Place cauliflower and broccoli in a large bowl. Add cheese, carrot, and onion.
Stir together mayonnaise, sugar, and vinegar. Pour over cauliflower mixture; toss to coat. Top with bacon. Cover and chill 1 to 8 hours.