Simon Wheatley

Provides a drop-down to select different templates for posts from the post edit screen. The templates are defined similarly to page templates, and will replace single.php for the specified post. This plugin will NOT switch the templates for the different posts in a listing page, e.g. a date or category archive, it will only affect the template used for single posts (i.e. you can choose a template which is not single.php).
Post templates, as far as this plugin is concerned, are configured similarly to <a href="https://codex.wordpress.org/Pages#Creating_Your_Own_Page_Templates" rel="nofollow ugc">page templates</a> in that they have a particular style of PHP comment at the top of them. Each post template must contain the following, or similar, at the top:
<pre><code><?php
/*
Template Name Posts: Snarfer
*/
?>
</code></pre>
First note: Page templates use “Template Name:“, whereas post templates use “Template Name Posts:“.
Second note: You must have the custom post template files in your theme in the same directory/folder as your index.php template file, not in a sub-directory/sub-folder.
<h3>Developers</h3>
If you want to implement the custom post templates on a custom post type, you can use the <code>cpt_post_types</code> filter, here’s an example below of adding the custom post template selector and metabox to the “Movie” and “Actor” custom post types. This code can be added to a plugin or to the <code>functions.php</code> file in your theme.
<pre><code>/**
 * Hooks the WP cpt_post_types filter 
 *
 * @param array $post_types An array of post type names that the templates be used by
 * @return array The array of post type names that the templates be used by
 **/
function my_cpt_post_types( $post_types ) {
 $post_types[] = 'movie';
 $post_types[] = 'actor';
 return $post_types;
}
add_filter( 'cpt_post_types', 'my_cpt_post_types' );
</code></pre>

Custom Post Template

Provides a drop-down to select different templates for posts from the post edit screen. The templates replace single.php for the specified post.

Gantry

<blockquote>
Gantry 5 is now available for WordPress! Please visit <a href="https://wordpress.org/plugins/gantry5/" title="Gantry 5" rel="ugc">Gantry 5</a> plugin page for more informations.
</blockquote>
Gantry 4 is a comprehensive set of building blocks to enable the rapid development and realization of a design into a flexible and powerful web platform theme.
<ul>
<li>
Please visit http://gantry.org to download a FREE WordPress Gantry 4 default theme which can be used as a base for your own themes!
</li>
<li>
For official RocketTheme Gantry forum please visit http://www.rockettheme.com/forum/gantry-framework
</li>
</ul>
Gantry 4 is packed full of features to empower the development of designs into fully functional layouts with the absolute minimum of effort and fuss.
<ul>
<li>True “Drag and Drop” page builder</li>
<li>Support for Responsive Layouts</li>
<li>LESS support</li>
<li>Syntax highlight support via Google Code Prettify</li>
<li>960 Grid System</li>
<li>Stunning Administrator interface</li>
<li>XML driven and with overrides for unprecedented levels of customization</li>
<li>Per override level control over any configuration parameter</li>
<li>Preset any combination of configuration parameters, and save custom presets</li>
<li>RTL language support</li>
<li>Built-in CSS and JS compression and combination</li>
<li>Flexible grid layout system for unparalleled control over block sizes</li>
<li>Optimized codebase with speed, size, and reuse core tenets of the framework design</li>
<li>65 base widget positions</li>
<li>38 possible layout combinations for mainbody and sidebars</li>
<li>Source-ordered 4 column mainbody</li>
<li>Many built-in widgets and gizmos such as font-sizer, Google Analytics, to-top smooth slider, IE6 warning message, etc.</li>
<li>Ability to force ‘blank’ widget positions for even more advanced layout customization</li>
<li>Flexible parameter system with ability to set parameters via URL, Cookie, Session, Presets, etc.</li>
<li>Table-less HTML overrides</li>
<li>Standard typography and WordPress core element styling</li>
<li>ini-based configuration storage for easy portability</li>
<li>Automatic per-browser-level CSS and JS control</li>
</ul>
For video tutorials and documentation please visit official <a href="http://gantry.org/" title="Gantry Framework" rel="nofollow ugc">Gantry Framework</a> site.

Gantry 4 Framework

Excellent Framework with plenty of options

Gantry is a comprehensive set of building blocks to enable the rapid development and realization of a design into a flexible and powerful web platform

Custom Post Template vs Gantry 4 Framework