Google calendars are used to track events, a way for organizing your scheduled works/tasks with easy accesses. In one of my Drupal site, I need to embed a Google calendar to create nodes on Drupal based on events from a Google calendar.
The Drupal panels helps the admin users / site owners to create a customized theme layout for multiple users in the site. This will help you to integrate with modules and can created the functionalities with the modules that use the panel features and permissions.