Chad Hovell

Select extra layouts from the post editor Screen Options menu. 
There are now 24 variations to choose from!

Three Column Screen Layout

Three, four and five column screen layouts for the post editor.

Jory Hogeveen

As easy as it gets. Add column classes to widgets with a select box, check whether the widget is the first, and save!
I’ve built this plugin for the Genesis Framework, though it will work with any theme that uses the (old) Bootstrap column classes.
You can also add your own classes through various filters to use this plugin with your theme’s grid framework.
<h4>Compatibility (IMPORTANT!)</h4>
This plugin does NOT add CSS for these columns. It ONLY adds the column classes to your widgets. The actual CSS should be added in your theme.
<h4>Filter: `genesis_widget_column_classes`</h4>
Allows you to change the available column classes
Parameters: <code>array</code> Default column classes. 
Return: <code>array</code> Array of column classes.
<h4>Filter: `genesis_widget_column_classes_capability`</h4>
Change the capability required to modify column classes. 
Since 1.2.2
Default: <code>edit_theme_options</code> 
Parameters: <code>string</code> The default capability. 
Return: <code>string</code> The new capability.
<h4>Filter `genesis_widget_column_classes_select_multiple`</h4>
Allow multiple classes to be selected. 
Since 1.3 
Return: boolean.
You can use these filters inside your theme functions.php file or in a plugin. 
You can find me here:
<ul>
<li><a href="http://www.keraweb.nl/" title="Keraweb" rel="nofollow ugc">Keraweb</a></li>
<li><a href="https://github.com/JoryHogeveen/genesis-widget-column-classes/" rel="nofollow ugc">GitHub</a></li>
<li><a href="https://nl.linkedin.com/in/joryhogeveen" title="LinkedIn profile" rel="nofollow ugc">LinkedIn</a></li>
</ul>

Three Column Screen Layout vs Genesis Widget Column Classes