Definitely buy the passes - they are much cheaper if you do all the exhibits or spend more than one day wondering around. We go pretty often although we haven't been in about a year. Our kids love it - it's very educational, but fun, too. Our favorite time is in Dec. for the "Grand Illumination" night - not sure if that's a possibility or not for you.
Have to see the Governor's Palace, Capital and the Magazine - but really,it's all good! So much of US history happened in VA at this time, it's very cool to see what it was really like. It gives you a great sense of history and the founding of our country. Definitely check out the craftsmen that you can watch make things like the did in the 1700's -
Try the gingerbread & cider they have along DOG Street (Duke of Gloucester Street) - my kids love that part.
Characters are scattered through out CW and that is my kids absolute favorite part - it's fun to talk to them! They never break character (close to disney quality! LOL)- and are often hilarious as well as educational.
Also Busch Gardens is great - and there's some good shopping at the outlets. (doesn't thrill my ds or dh at all. LOL)