Warning: my not-too-subtle opinion on this matter has been influenced by real-world experiences with server systems that had a GUI. My advice would be not to implement a server GUI. The reasons are
Contrary to popular belief, GUIs are in many cases (including this one) not more user-friendly than text interfaces. They are more beginner-friendly, but that is something different altogether. It never fails to amaze me that in this industry "user-friendly" and "beginner-friendly" are so often confused.
Servers should be scriptable so that they can be started, stopped and managed automatically. Scripting a GUI is hard or impossible.
On Unix systems, a GUI requires the presence of an X server. A lot of serious server iron does not even have a graphics card, let alone an X server. And I can tell you from bitter experience that simply pointing the server at an external X workstation is a bad, bad idea.
For these reasons, if there is a GUI, it should be optional. Full stop. And that is likely to be more trouble than you want to go through. - Peter