I think you can find more than enough to do without the amusement park and beyond Colonial Williamsburg itself.
A visit to Jamestown is totally worth it. If you are a real lover of historic sites take time to visit some of the many other plantations and historic houses in the area and include a trip to Yorktown. Or should you be inclined toward the water (as I am), try one of the tall ship cruises or sailing trips.
Shopping on your list? Make a stop at Yankee Candle Company, MJF Silversmith, and a host of galleries.
Are you an outdoors buff? There is a wonderful biking opportunity (or driving) in the 23-mile Colonial Parkway, lots of biking and hiking trails, kayaking to Jamestown Island, lakes, beaches, fishing. You name it.
Virginia is a gorgeous state. Have fun!