Thinking in terms of engagement, rather than experience, architecture, or interactions, has opened all sorts of doors for me, whether I'm consulting, publishing, or whatever. I look at every potential relationship between people involved in an experience, and ask "How we engage better?" and "How can they have a stake in what we're doing?" To me, that's much richer than asking how we can help users interact better, or help them find better, or entertain them better, or anything else.
