One of our favorite locations in the area near the venue is the National Mall in Washington D.C. There are a plethora of activities, historical monuments, and the famous Smithsonian museums that are free to the public. You could spend days here and not see it all. There are lots of access from the metro to avoid high parking cost. If you are driving there keep in mind that traffic can be very bad in the surrounding areas. It is approximately 1-2 hours away from the venue depending on traffic.
There are a decent amount of breweries and vineyards in the area surrounding the wedding venue. Fredericksburg, VA has a few award winning brewers. Our recommendation is Strangways Brewery.
A great museum in the D.C. area recommended by both of us that is well curated and thought provoking.
Arlington National Cemetery and the Tomb Of The Unknown Soldier is a captivating display of those who gave there lives in our military.