Delp's post in weekly , monthly missions and clan missions was marked as the answer
I personally like the idea of Weekly and Monthly missions.
In my opinion weekly missions could include raid points destroying, some big cbk type mission (for example 100kills), collect some item. It would increase danger zone activity.
When It comes to monthly missions I would like to see some "kill X boss type" etc. It would bring more activity into zones which are usually empty.