Tension is an interesting quality - and architecture must have it. There should be elements of the inexplicable, the mysterious, and the poetic in something that is perfectly rational.
Architecture is about aging well, about precision and authenticity. There is much more to the success of a building than what you can see. I'm not suggesting that gestural architecture is always superficial, but solid reasoning has its place.
The secret of good architecture is having more than meets the eye.
Everything is complicated about using concrete - the discipline and dedication necessary to make consistent batches, understanding exactly how the formwork will be laid, what the timing is for the pours, how you keep it clean and neat to achieve a fine quality.
I know I'm old-fashioned, but there's just something about the act of looking at books versus taking in information on a screen, which is so one-dimensional. There's a sense of ownership that you have with books, a physical connection.
There isn't any one material that's mine. It all depends on the context. For example, I did a house that had the most exquisite marble applications. That sounds ostentatious, but it wasn't, given the context. The color white I subscribe to extensively. I love thinking about color, but I often go with white.