Washington D.C. is definitely a spot you should visit. Here are some of my favorite locations in the area: Roosevelt Island, Bike Trails between Roosevelt Island and Mt. Vernon, National Cathedral, the park just north of the airport, the National Arboreteum, Smithsonion's (My favorites in order: Natural history, art, U.S. history), the capitol and white house, Washington monument, Lincoln, Jefferson memorials, Korean and World War II memorials, Shenandoah Mountains and George Washington National Forest (hiking), Harper's Ferry and vicinity, Baltimore, Williamsburg. Best wishes on retirement.