I like using gnome-gmail for the simple reason that it makes is possible for me to use gmail as my default mail handler (as configured in System Settings:Details:Default Applications in 16.04).

Ubuntu 16.04 Default Applications dialog

I should note that I am using Chrome and I have saved each of my preferred google web apps to Desktop using (More Tools:Add to desktop) in Chrome browser then adding those to Launcher so they open like apps.

Is there a similar package or method to make google calendar the default handler for calendar items (e.g. .ics)?