I love Williamsburg, but haven't been there for years. You'll have a blast.

(1) Get lunch at The Cheese Shop in Colonial Williamsburg (CW), right near the Wren Building at least once, and eat your sandwiches on the quad at the College in the sun;
(2) also get a snack of "bread ends and house" [dressing] at the Cheese Shop at least once, because YUM; and
(3) eat dinner at least once at the Trellis restaurant, also in CW, and save room for dessert, because the chef is justifiably famous for his chocolate desserts. Probably wise to line up reservations for the Trellis.
Skip the various colonial-themed taverns; the food is overpriced and undertasty.
I got a thrill out of attending classes in the Wren, in the same rooms where Jefferson and Washington studied, but I don't know if just walking around in the building would be the same.
The old campus is gorgeous and worth a tour, if that's your thing. The new one, eh, not worth it.
Have someone direct you to the -- oh, I'm blanking on the name, but there's a very pretty bridge, and anyone on campus will know what you're talking about if you say you're looking for the bridge. There's a legend that, if you kiss your beloved on the bridge, you will marry that person -- which is true if only because as a result no one kisses on it unless they're engaged or in the process of becoming so. You know, just in case.
If classes are in session, and the improv group (I.T.) is performing while you're there, go see them. They have a well earned reputation for being one of the best college improv groups in the country.

Thank you so much for these tips, Sheila. It sounds incredible. I can't wait to get out of Jersey and down to Williamsburg for the vacation.