Too much wide open. I guess it is cool if you are into history. I cannot control or change what happened 230 years ago so I would rather focus on today. Others may not share my views because there are cars from all over the country at the visitor center. There are also limited hiking trails in the park.
Yorktown Battlefield park has road biking not mountain biking. I have been twice now and had a good time. Rode from George Washington's Headquarter to the French encampment and back. The trail is the tour road so you have to share it with cars. The speed limit is 15mph. We saw only one car the whole ride. Saw several bike riders, joggers and walkers. There is a connecting trail at Washington's headquarters to the Newport News Park Bike Trail (5.3mi). This is the off season for Yorktown Battlefield so not sure how the ride would be between Memorial Day and Labor Day.