We live in Va and go to Wllbg all the time. April can be iffy--weather could be OK or rainy and cool. Thanksgiving is the same way---in can be rainy and yucky, or just really cold. End of June is usually good, of course hot and crowded. 3rd week of Aug. is much less crowded. Sometimes a tropical storm might be coming thru and it is hot. All of the above weather has been experienced by me 1st hand at Wllmbg!
Where I have stayed and liked: Governor's Green (decent units, good pool, very convenient), Greensprings (somewhat outdated decor, but very nice units, fabulous beds, great pools--very nice indoor pool, large jacuzzi, sauna---I would pick here for April or Nov b/c of the pools), and we have been in Fords Colony (a bit farther away from Old part of Wllmbg), but I am very partial to the Marriotts and would stay here, if the prices were the same as the others. Plus, MArriott will have kids' activities. However, Greensprings is similar quality to the Marriott, IMHO.
I have also stayed at Powhatan and Patriots Place--I would consider those only if the above were not possible.
If you wanted, you could probably easily transfer some of your
DVC points to someone on TUG and work out a trade. There are a number of us TUG members who have other timeshares as well as DVc points.
Also, you can book many tours, etc. in advance at history.org. Elaine