Denim is an American wardrobe staple and something that is in most of our closets in multiples. However, when summer hits, it may get a a little less airtime especially if you live Ina city like DC where the humidity makes anything heavier than linen feel like a death sentence.
[Enter stage left] Denim....in white. More specifically, a white denim dress - this one available at Topshop. It's not quite appropriate for work but movie night, date night, girls night out, after-work/weekend drinks....you're in business!
I'd mix it with a print shoe or handbag and let the dress do the rest.