Can anyone suggest a day trip from DC. We have been to DC several times and wanted to explore outside the city. We have been to Baltimore and Annapolis. Where else do you suggest.
Thanks

Mount Vernon - http://www.mountvernon.org/visit/directions/drive.asp

St. Michaels is a quaint harbor town on the eastern shore a 1 1/2 - 2 hours away.

Old Town Alexandria, VA, is a larger town with waterfront area and quaint shops about 1/2 hour away.

Try the Brandywine Valley area of Delaware/Pennsylvania, which is just about a two-hour drive (and can be reached by Amtrak trains, also). Many of the attractions there are former du Pont family mansions turned into museums and gardens. There's also a museum with the works of three generations of the Wyeth family.

Shenendoah National Park's Skyline Drive is a beautiful way to spend a day!

harpurs ferry -- historic and also you can raft or tube in the area rivers; gettysburg; antietam; all very do-able

Wine tasting at the wineries in Virginia.

Charlottesville.

Another vote for Skyline Drive, and St. Michaels.

And for Harper's Ferry (it's only an hour drive).

Frederick and the state parks nearby, e.g. George Washington Monument State Park, Greenbriar State Park (?) Cunningham Falls SP. Go the the Maryland State Park website.

Frederick and the state parks nearby, e.g. George Washington Monument State Park, Greenbriar State Park (?) Cunningham Falls SP. Go to the Maryland State Park website.