General admission ($20 per person) is required for entrance. After that, they have different rides/tours ("train", boat, or the house, etc). These added attractions are $8 each/person, but are worthy, we did the train and had a really good experience. I recommend buying tickets at the entrance. On their website there is a coupon that gives you a free ticket for the purchase of one general admission ticket, just print it out and bring it with you. This was fantastic for us, we saved $20! We went on a Thursday, so there was no line at all. Not sure how busy is the plantation during the weekends.
The "train" (a motorized people mover) takes you to several of the outlying sites. Definitely worth it.
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