While you're in DC, check out the TruthBeauty show over at the Phillips Collection, The Pre-Raphaelite Lens show at the National Gallery of Art (I think it's in the West Wing), and then just take a stroll up the hill to the National Portrait Gallery/Museum of American Art. I don't know that they have anything specific on display right now, but the NPG/MAA is THE best place in DC to see photography.