We have walked the trails of Great Falls countless times! River Bend Park is where we met for our first bike ride and it is a lesser known spot to enjoy the quiet and nature in Northern Virginia.
We have biked the streets of D.C. a few times and Shannon has run the length of the Mall many mornings. It's lovely any time of day, but seeing the monuments at night is a great experience. Suggested place to park: West Potomac Park on Ohio Drive SW.