One of the best time to be in Washington DC? During the Cherry Blossom Festival....
When during the festival? Well one of the best time is certainly at sunrise. Not only you will enjoy a beautiful sunrise above the Jefferson's Monument, great light the first hour after the sunrise, but you won't have to be in the crowd (if you're like me going around with a stroller, kiddos and a tripod, that may be a big thing to consider!).
And the same old tip, change angles, change perspectives, zoom in and zoom out!