>> When emacsclient is used in a terminal, emacsclient FILE opens a 
>> non-graphical Emacs frame, and emacsclient -c FILE always creates a new 
>> graphical Emacs frame. A third option, which creates a graphical frame 
>> if none exist and reuses a graphical frame is one exists, would be 
>> useful (see for example [1] and [2]).
>
> It seems like tons of users are using home-cooked solutions and scripts 
> to do this, so there is a clear need for it.  I think we should add it.
>

Thanks for your comment!

> Your patch LGTM, but it's missing a NEWS entry.
>
> (Perhaps we could also update the man page, but that's no requirement as 
> we don't really make an effort to maintain it.)
>

Updated patch attached.