Guild headquarters instance
Guild Halls were in Guild Wars 1. It was over a year ago, but I attended PAX Prime and went to one of the conferences. Eric Flannum mentioned that they would not be in launch, but are in development. So, I expect to see Guild Halls in the future.
As for Guild Unity, I often get called a jerk for saying this but don’t pick a guild that often recruits in global/map chat. These guys are mainly people that just want numbers. The best way to find a guild is to make sure it’s a fairly large one with a diverse group of players and find them by the actions you do with them, not by asking for a guild in map chat. You’ll often find a guild that’s pretty bad or plays solo and uses guild chat as another chat box if you just join one with someone that recruits often via map chat.
Im in a great guild, they are helpful if you need questions answered and plenty of chat, but there is no need for guild members to assist you or do any kind of large scale challenge in pve. I mean you can ask if anyone wants to go do a dungeons but pugs work too. REally there is nothing that you need a guild or in this game(only talking PvP)
I agree with this, A place for guild members and alliance to hangout.