Save your money. Rent a car. The entrance fees to the plantations are under 25 each.
My rating is based solely on the timing of this tour. The first stop was Laura Plantation where we took a wonderful 90 minute tour. Our guide was absolutely amazing in telling the story of the family that lived in this plantation. However, Oak Valley was visited in a rush. There is a 45 minute narrated tour through the house and then we were only given 20 minutes to explore the grounds and eat lunch. Obviously not enough to do either. There is a restaurant on the grounds but there was no time for that. I would have preferred extending the tour by an hour to give people the time to explore or have a nice relaxing lunch prior to heading back to New Orleans.
Really enjoyed the tour but would have like an extra hour and a half at Oak Alley to be able to see everything and eat.