I hereby throw my humble unbiased opinion out at my screen and hope I get some responses.
Jukeboxes. In the guildhall, perhaps as a room or item available for purchase, they would allow you to change the music that plays in your guild (such as the glorious theme that used to be in the guildhall and is now only able to be heard in the moorcraft manor or gremlin clockwork place thingy). Perhaps not even the jukebox itself, but an option in the design mode of guildhalls that you could access to change what would play when in the guildhall (much similar to the ability to change weather/climate).
Just a thought that I hope will gain some opinions and possibly even be added! :o
This has a good idea in theory.
How aboot we make it that players close to it can hear the music and you can change its song to any songs bought by the guild for lets say, 2000 crowns. 1000 goes to the guild and the other 1000 just go poof. Why go poof? to help lower the crowns circulating. I know they probably will go poof from guild rent but its just a thought!
Make each song unlock vary from 10,000 to 50,000 depending on how special the song is. Maybe require the guild to "craft" boss songs or some thing. We could include special song unlocks that guild leaders can use for purchasing the song packs of SK.