Poplar Forest (in Bedford County) and the Virginia State Capitol (in Richmond) are proposed as an extension to the Monticello & University of Virgina site which is already on the WH List. After having visited Monticello in the early morning, I drove 1.5 hours to the South to Poplar Forest. This was Jefferson's retreat and included a large plantation. He designed it after Monticello (starting in 1806).
The property is located in the woods somewhat outside Lynchburg. I noticed that the modern day occupants of this area have very nice houses too!
There were a couple of other (elderly American) visitors around when I arrived. The guided tour here (10 US dollar) is slower and more in-depth than the one at Monticello. Poplar Forest is still undergoing restruction to re-create the time when Jefferson lived here. The house was in private hands until 1984 and at that time had been altered significantly. The walls are still barren now and there's almost no furniture in it. This however shows in detail the way this house (and Monticello) was built. A lot of the features of Monticello are here too: the skylights, the long windows and the servants quarters underground. Looking back, I am glad I have visited both Monticello and Poplar Forest: seeing both deepens the experience.