Might as well see Colonial Park (Yorktown) as it's right down the road from Colonial Williamsburg. If you're also going to the Smithsonian, drop into Mt. Vernon and see the house that George built. George Washington's house is run by the DAR and they've kept it in very good condition. Bring a bag lunch as their fast food sucks (their regular restaurant fills fast). The George Washington Masonic Monument in Alexandria is free and there's plenty of free parking at the monument. There are some artifacts belonging to our founding father there on display. Carlisle House in Alexandria is open to the public and that's where Braddock lived while he planned his ill-fated jaunt into the woods. Carlisle was fed up with the haughty Braddock and glad to see him finally leave.
More Civil War oriented: Harper's Ferry, Lee's House in Arlington National Cemetery, Fredericksburg (Old town) is worth see as is Chatam (sp) Manor (across the Rapphannock and still part of the National Park System). If in Richmond, the Virginia Historical Society (all periods of Virginia History), Museum of the Confederacy and Monument Blvd are worth seeing. So is Tredegar Iron Works & Chimbarazo Medical Museum (part of Richmond National Battlefield Park). John Marshall (as in Chief Justice) house is within walking distance to the Museum of the Confederacy and parking for the Museum of the Confederacy is free (validated at the museum) from the adjacent hospital. There's no shortage of battlefields including Williamsburg, Dam No. 1, Petersburg (want to see Civil War forts?) with the Crater (Cold Mountain) & nearby Five Forks, Drewry's Bluff, Gaines Mill, Malvern Hill, Seven Pines, Savage Station, etc. The Monitor Museum is down at Norfolk and they're building a full scale replica of the cheesebox on a raft. Also in the area of Richmond are Spotsylvania Courthouse, The Wilderness, Chancellorsville.
I haven't been to Jamestown but was told by Williamsburg staff that it is worth seeing.
If you like aeroplanes, drop into the Virginia State Aviation Museum. They have a SR-71 parked outside and there's a monument to the first military aeronauts (balloonists both blue & grey) there.
West of Richmond is Appomattox Court House where Lee surrendered.