Depends on what you're looking for. If you want trees and nature, then I recommend the Newport News Campground. It has a stocked lake for fishing, boating and such. Lots of trails, archery, playgrounds...that kind of thing. The sites aren't especially level and the bath houses aren't as clean as the fort, but we like it. I'd prefer to be surrounded by green and parked near the lake myself.
http://www.nnparks.com/parks_nn.php
If you want level, paved sites then check out American Heritage RV park.
http://www.americanheritagervpark.com/
Both of these campgrounds are close to the historic triangle and bush gardens. Anyplace you go though, you may have some train noise to contend with. Neither of these is as bad as the Anvil campground which sits a bit too close to the tracks, so I'd stay away from that one.
Hope this helps! Williamsburg is one of my favorite places to visit! In fact, I'll be there in a couple weeks, so if you want any info I can try to get it for you!