It's a funny thing, which has happened to me several times, that the best shot is the last shot you get; and is not the one you expected.
I went to New York quite frequently during Winter 2014 to prepare my book. After weeks and weeks of work, the book was finally finished and on the last trip my wife was with me. That day we had gotten up in the middle of the night to get some interesting shots of the empty streets of New York, so we were exhausted. It was around 7:00 pm and my wife and I were falling asleep, when all of sudden it started to rain. I was in bed, but the metro station, which was right by our hotel, haunted me, I loved the look of it. I then realized that the rain during dusk could make a very cool shot. I went there and it was amazing, it felt like I was on the set of the Dark Knight movie.
I got the shot, which was the last shot that went into the book, and went back to see my wife still sleeping. I showed her the photo and she couldn't believe it – we loved it more than anything we had done in the past few days.