Amazium, Bootstrap and Foundation Grid Templates
Amazium has 12 columns also and states that it supports rapid prototyping, resizes itself neatly, has "pre-made" buttons (great for nav) and seems to respect typography and legibility right out of the gate. The best thing about Amazium, pertaining to my hybrid app, is that I can focus on my code for the content, while it is "resizing [your] content using 4 media queries (1200px, 960px, 768px & < 767px)." (Credit)
Foundation is very clean and has a business style approach, with many of their clients from a medium to large size business background. This specific site didn't have docs immediately available on the main page (acting like a walk-thru), but does make it easier to explain how it supports prototyping, uses Intercom platform to chat with website visitors (almost like instant messaging, so you can receive a reply most efficiently and quickly), and allows you to edit what framework components the coder will need.
Bootstrap is really very cutting edge also, but offers an option of selecting a "theme" to apply to the bootstrap framework. This is something unique because it will almost be entirely designed for the user, cutting down on time spent coding and testing. Beneficial in this template, it also offers a customizable page where you can "fine tune" your product to eliminate some of the non-essentials.
