We just spent a week in Massanuttan, VA and time in Williamsburg, VA so this question is current in my head. I second bring ziplock bags, tin foil and paper goods. Bring jugs of water, I have become a water snob in my old age and I just did not like the taste of the water there and had to pay way too much to stay hydrated. We did a Costco run and a Trader Joes run before we left. We brought pre-made soups, roll-ups (turkey wraps), cooked chicken, bread rolls, prewashed salad, baby carrots, cheese, meat slices, pickles, olives, crackers, fresh fruit, cereal, milk, hot chocolate, coffee, cans of tuna, peanut butter, etc.
We usually had 2 meals in and sometimes 1 meal out. Sometimes we had brunch and dinner and grazed and snacked the rest of the day. If we were out playing tourist we went out to eat one meal. Breakfast was an easy meal to pull together - instant oatmeal worked great. If we were away from the timeshare I packed picnic sandwiches, stuff that I would send to school and work and had one meal on the go.
I was about EASY meals. I had no interest in cooking, reheat and serve was my mantra, If I spent 15 minutes on food prep it was too long. We did bring our pinnini maker, that was fun.
I packed our favorite games which was great, a family movie we all wanted to see and kid DVDs so they could have their down time in their room while the grown-ups hang out or prepped a meal.
Also, we brought a hand soap pump, which I wish I had brought 2 more. A bottle of laundry soap. Extra paper towels and someone suggested to bring toilet paper and extra towels, (which we didn't need but would still bring again because some time shares charge to replace those.) Where we were had a water park and we did bring our own pool towels which was very useful.
The craziest thing we brought was my favorite blanket from my bed, but since we were driving, we figured why not and I was so glad we had it. It made sleeping much easier and our travel mates were cold at night.
Since you are in DC and I am in Virginia Beach I am wondering where you are headed, it sounds nice and maybe we'll try it out on our next timeshare adventure.
Have fun! If you have any more questions or want to bounce some ideas, please feel free to send me a message.