It was quite challenging because of the crowd, not having a comfortable place to setup and paint and nervousness :-) Also, the subjects were intimidating and complex. I am glad I did it though, and even though the sketches didn't turn out as good as I would have liked, it is a start and I like to believe that they will get better.
I did a quick pencil sketch first for each of these paintings, and that helped me get to know all the elements and map out the big shapes. I am happy that I am making this a habit now, to do a value sketch before jumping into the painting.