Good CSS comes from having great html. Organization is key when working with a team and having a solid pattern for writing HTML content is the first step in achieving modular stylesheet patterns.
Let me start by saying I'm a huge fan of HTML tags. I try to use them as often as possible so I don't have to rely on creative CSS names and ID's for every HTML object. I'm also a big fan of full width containers. When I think about HTML (cause we all do all the time, right?), I don't see the content as one long strip wrapped up in one package. I see the content as blocks, or 'sections', to be placed like bricks on a device (grid structure is very important here). Writing as modularly as possible helps organize HTML content.
Here's an example of a typical HTML and LESS I'd write for a responsive project:
The content contained within independent sections can interact in unique ways as the page isn't limited by any margins ('think outside the bun'). The concept is the same as the traditional wrapper, the only difference however is we've taken that concept and used it to define sections of pages rather than the entire page. Contributing is always better then constraining.