Google is giving you one good reason to start (backing up your photos) using Google+ by adding the new Insert Photo button on Gmail.
Currently available on the web version of Gmail, this new feature allows you to instantly access all the photos that are backed up on your smartphone using the Auto Backup feature of Google+. All you have to do is select the photos you wish to send and click insert. According to Google, you can also upload an entire album and resize images while composing messages.
If you're not yet using the Auto Backup feature on Google+, you can start by turning it on either on your Google+ Android or iOS app, or on the Google+ Auto Backup for desktop and Chromebooks. To learn more about how to use Auto Backup, visit https://support.google.com/plus/answer/1647509.
Images from Official Gmail Blog