Pierre-
I spent a few very enjoyable years in Williamsburg as a grad student at William and Mary. It's a really nice place! My suggestion would be to NOT try to do too much and make life simple for yourself.
Fly into KJGG located right on the James River in Williamsburg then rent a car. The airport is about 2-3 miles outside the town's historic center.
The three "biggies" as mentioned above, are CW (Colonial Williamsburg), Yorktown Battlefield (the National Park Service site), and Jamestown Island (again, the National Park Service site). CW is a day in itself probably and also has lots of great little shops called "Merchant's Square" at one end for those who like shopping and/or don't like a full day of playing history buff. Both CW and Merchant's Square lie directly across the street from the historic William and Mary campus, the second oldest university in the US, and really nice to walk through. Jamestown Island is the site of the first English settlement in North America and really great for those who like archaelogy, and Yorktown is the site of the last battle of the American Revolution.
I would also highly encourage you to take the drive between all three sites using the "Colonial Parkway."
http://www.nps.gov/colo/parkway.htm It is a very pretty road and, literally, was built to connect those three (Yorktown and Jamestown each at one end, with CW in the middle). Much of the way it is right along the James or York Rivers. You can get to those places through other side roads and highways, but it's not nearly as pretty. In fact, if you spent one day at CW, you could easily do Jamestown Island and Yorktown Battlefied (with the parkway drive in between) on the second day.
Finally, if kids are involved (or adventure-seeking adults), Busch Gardens is one of the neatest amusement parks in the country. Unlike most others that are built on a big slab of concrete, Busch Gardens in Williamsburg is built into the forest. Lot of fun.
There are tons of good restaurants in Colonial Williamsburg and Merchants Square and many nice hotels as well. Just depends on how much you want to spend for the latter. The closer you can stay to CW, the more "historic" or authentic feeling the place will generally be.
This was the standard itinerary for friends and family who came to visit. It's a great weekend trip if you don't try to pack too much in, so have fun!