Yorktown Riverwalk area is nice
http://www.riverwalklanding.com/ , Yorktown pub
http://www.theyorktownpub.com/ has some good pub food, I like the fried oyster sandwich. There is a farmers market every Saturday through summer now with some stuff going on, but you won't be around for that I see.
Across the river in Gloucester there is a nice marina
http://www.yryh.net/ with a good restaurant and crab deck
http://www.riversinnrestaurant.com/ with good food and drinks. Looks like it just reopened. The marina is a higher end full service type marina, lots of docks to walk, some big boats etc. This place is located on Sara's creek, which is one of our favorite not so far away destinations when we are looking for a place with a restaurant etc. We also like to take the motor boat there just for dinner.
Pierces Pit, as someone mentioned has good BBQ sandwiches in Williamsburg, make sure to get the pulled pork sandwich and when asked if you would like coleslaw on it, say yes!
Wednesday evening races on the York River (viewable from Yorktown I believe) as well as in races in Hampton wed evenings too. Yorktown has a long fishing pier as well.
We'd be happy to have you over for dinner out on York Point in Seaford (close to Yorktown), or meet up somewhere while your around. Send me a PM if interested.
Enjoy the area, we do!