Complexity can sometimes be a perspective thing. I recall a discussion at one point with a co-worker were we were each arguing that the other persons approach to a particular problem was more complex. After much contemplation I was able to see both perspectives.

Also with some problems there seems to be a conservation of complexity notion. It's inherent in the system and depends on where you push it.

For the book, you might want to check out Large-Scale C++ Software Design. Unfortunately it's at home so I can't crack it open and double check, but it seemed full of suggestions on structuring code and layout a large software project.