I've been reading "JavaScript Web Applications" by Alex MacCaw and it provides a great introduction to MVC and a number of popular client-side frameworks. It also contains a ton of best practice advice for general JavaScript development. Definitely worth checking out.
I would recommend Alex Maccaw's javascript Web Applications. Sure it's about Javascript, but how really big can your HTML/CSS get before you modularize? :) What I like about the book is that it explains the fundamentals of MVC in a framework agnostic way, which I think is helpful if you are trying to refactor and MVC-ize your code base without throwing in a heavy dependency like Backbone or Spine.