The one touristy thing I felt like I had to do before I left DC was see the monuments at night. Sunny brought it up when we were planning out the trip and I latched onto the idea, so my last night in DC Sunny, her boyfriend Evan, and I had dinner and then walked through all the monuments after the sun had set. The little walking tour Evan gave us was great, we went from the lavish World War II memorial to walking along the pond towards the Lincoln Memorial, and then through the much more somber Korean and Vietnam War Memorials. I didn't go by the monuments in the day, so my opinion doesn't mean much, but I feel like this was the best way to experience them.
It was a lovely night walking through the city with friends.