Drupal 7: Page template hook for content type

node_type_page.php

<?php
/**
 * Variables preprocess function for the "page" theming hook.
 */
function THEME_NAME_preprocess_page(&$vars) {

  // Do we have a node?
  if (isset($vars['node'])) {

    // Ref suggestions cuz it's stupid long.
    $suggests = &$vars['theme_hook_suggestions'];

    // Get path arguments.
    $args = arg();
    // Remove first argument of "node".
    unset($args[0]);

    // Set type.
    $type = "page__type_{$vars['node']->type}";

    // Bring it all together.
    $suggests = array_merge(
      $suggests,
      array($type),
      theme_get_suggestions($args, $type)
    );

    // if the url is: 'http://domain.com/node/123/edit'
    // and node type is 'blog'..
    // 
    // This will be the suggestions:
    //
    // - page__node
    // - page__node__%
    // - page__node__123
    // - page__node__edit
    // - page__type_blog
    // - page__type_blog__%
    // - page__type_blog__123
    // - page__type_blog__edit
    // 
    // Which connects to these templates:
    //
    // - page--node.tpl.php
    // - page--node--%.tpl.php
    // - page--node--123.tpl.php
    // - page--node--edit.tpl.php
    // - page--type-blog.tpl.php          << this is what you want.
    // - page--type-blog--%.tpl.php
    // - page--type-blog--123.tpl.php
    // - page--type-blog--edit.tpl.php
    // 
    // Latter items take precedence.
  }
}
?>