At Big Brush Agency we love Yii and really want to give our contribution to the community. Big CMS is a open source Yii 2 application, with frontend and backend, ready for shared hosts. It is ready to use after installation but actually created as an development platform with features used in common web applications.
Big CMS is still being developed but is ready to be installed and played around with. It can be installed via composer and the console. A demo site has not been created yet, but will be available in the near future (i believe it is so easily installed that it kinda equals a basic demo site).