I am using Tiling Shell

https://extensions.gnome.org/extension/7065/tiling-shell/

Puppet / Foreman / Ansible for managing servers, and probably for workstations too.

Checkmk / Nagios / Zabbix for monitoring.

FreeIPA for user management.

I am working in company where about 35% of users are on Windows, 40% on Linux and 25% on Mac. In Linux, official way to use MS Office is web apps, but Libreoffice is quite heavily used too.