I'm pretty sure these have come up previously, but the current Guildhall layouts certainly look like they're waiting for materials storage to be implemented, and maybe such as statues on those currently-bare plinths flanking the entry corridor. The Treasury thing is a cool idea - pooled resources are one of the few really useful functions of Guilds as they stand - but I'd suggest that any withdrawals be approved by either the Guild Master or (preferably) promoted Veterans. I LOVE the bulletin board and alternate exit ideas; after all, there are already three corridors leading south out of the Guildhall (even if two of them are currently barricaded), so why not have exits to the Town Square, Bazaar and Arcade?
What I want most out of my Guildhall is functionality and customisation; as it stands, they have neither. My Guild's recruitment policy is pretty stringent - basically it's IRL friends only - and currently acts as a handy way to separate the casual contacts I've made in the game from people I actively hang out with, but that that's almost its sole function is, frankly, rubbish. I want my Guildhall to reflect the achievements and, ideally, tastes of my Guild. Let's not forget, also, that allowing players to add items to their Guildhalls - whether functional (traders, storage lockers, bulletin boards &c) or purely decorative (statues, banners, Fallout 3-style themes &c) - has potential to be a fantastic CR sink, an extra something to keep players hooked on lucrative runs long after they've cracked Tier 3 and are running out of things to do.
There's a rather hokey browser MMO called Legend Of The Green Dragon that sports a rather basic, but helpful and compelling, Clan mechanic. It's text-only, so obviously customisation is limited, but it at least allows Clan Leaders to alter stuff like a Clan Hall MOTD, clan descriptions - tiny things, totally unimportant to the gameplay, which nonetheless make players feel more involved and invested in their teams. Clans have gold and treasure vaults that players can add to freely, but which require Leader or Officer approval to make withdrawals from. There's a Clan Buff system which would probably horribly unbalance SK - basically, members can add treasure to a separate vault, which goes towards permanent character buffs for members of that clan, approved by the clan leader - but it's a good example of a mechanic that actually makes clan allegiance meaningful and useful.
Edit: can we please keep PvP talk out of this thread, do you think? The boards have more than enough cluttered here's-everything-I'd-change topics already.
the arena would be like the PvP, "Not balanced". But! Maybe we could change it around to make it like a contest. a few of my ideas are: Survival(each player has to survive hordes of 1 specific enemy type randomly chosen like: Devilites and Kats. Zombies and jellies, you get it.), Race(yeah i know kinda kiddish. It would be an obsticle course to the finish.), Horde(Randomly chosen enemies of all types. The tier is chosen by leader of party soo... Tier 1 would be easiest difficulty, Tier 2 harder and Tier 3 hardest.) and finally Boss Run(you can change difficulty from very easy to hard. The bosses would be easier/harder depending on what * item you use and difficulty you choose. The bosses would give out more/less tolkens depending on how well you did and difficulty. if the party is still standing you can heal yourself up and defeat the bosses with hordes of different enemies and trojans in an arena.). I think those idea's would work pretty well don't you think?