We're going to DC for a long weekend towards the end of April. Are there some mild to medium hiking trails that you would recommend? I know we'll get tired of all the memorials / touristy things.
Thanks

Try going just West of town to the Great Falls area. There's a National Park. You can hike along some mild trails and see both the Great falls which should be roaring in April and the historic C&O canal locks as well.

I second the recommendation for Great Falls. Very worthwhile, some decent hikes and great views of the falls. Roosevelt Island is another good choice, on the Potomac. I don't think the views are as good but it is closer in.

I'm not sure whether I'm remembering this correctly, but I think on the Maryland side, there's a park or area called Potomac Falls, where you can hike along the flat C&O canal and see Great Falls. Someone please correct me of I'm wrong. There's a lot of good hiking in the countryside outside D.C. The Catoctin Mountains, near Camp David in Maryland, are maybe an hour away and there are parks and the like with good hiking there, too. But Great Falls are closer in, which might be better for a long weekend.

Here's a link you may find helpful:

http://www.recgov.org/r&w/nihhiking/NearbyHikes.htm

The Billy Goat Trail is pretty popular.

Also, just off the GW Memorial Parkway is Roosevelt Island:

http://www.nps.gov/this/pphtml/activities.html