After doing a quick search for "guild hall" under the suggestions sub-forum, I find lots of people have the basic idea of what needs to happen with guild halls. Currently, they're kinda useless. Some ways to make them less useless would be too...
-Voice chat in Guild Halls. This seems like a no-brainer, as if you can chat like it were in the Clockworks, why can't one use voice chat?
-A Player list of who's in the Guild Hall on the side, again, like in the Clockwords
-Decorations! Couches, banners, water coolers, TVs, podiums, whatever! Anything that can make a Guild Hall special to the guild. They can be purchased for different ammounts of CE or Crowns.
-A bank for the guild. This is one suggestion I see a lot, and think it is a good idea. Players can put crowns or CE in the bank, which can be accesed from the Guild Hall. The bank will look like a giant vualt, maybe slightly ajar, with crowns and CE spilling out. Aesthetics are everything.

I know a lot of people have different suggestions, but these are my opinions. I would be glad to hear yours.