Define custom view page template with theme_hook_suggestions
Your approach is fine. The only problem is with the name of the hook suggestion and the equivelant tpl.php file.

Since you are preprocessing views_view the hook suggestion should be named something that starts with views_view ex: views_view__[anything]. Note that all the undersores will be replaced with dashes for the filename. So it should be something like views-view--[anything].tpl.php 

For example:

/**
 * Implements hook_preprocess_views_view().
 */
function MYTHEME_preprocess_views_view(&amp;$variables) {
  // Some logic to decide if the hook_suggestions should set or not
  // ...
  $variables['theme_hook_suggestions'][] = 'views_view__foo';
}


And the filename will be views-view--foo.tpl.php