Having my mains in the RP guild I've been fighting to rebuild and grow means, to raid with my friends in our sister guild, we miss out on guild perks, on guild achievements, and one guild is leveling far slower than the other. I am still really ambivalent about the guild leveling system due to what it does to new or niche guild concepts, and the people in them who want to raid with friends.

Luckily most of the people I know do just want to get together and have fun, whether it be at a RP event or running a raid, and screw the guild tags and subsequent achievements (though it's always nice to get them too on random occasions). While the support to go run dungeons or raids with folks you know is nice, most people play with or know more folks than just their current guildies, even in family/friends guilds.

People are why I still play WoW. The content's nice, I enjoy the story bits, I like beating up pixels to unwind, but I can get that from any game. The social aspect of WoW is what keeps me subscribed, and my social circle is more than my guildmates.

Piper, while I'm not sure if it will have the option like RealID when it comes out, but I know realid has the "create conversation" option (requires at least 2 other people to use though), and I'm hoping BattleTags gets that as well.

In Guild Wars 2 guilds will be cross-sever, and you can belong to as many as you want simultaneously.

Personally I've found raiding guilds I've been in to be far more social then most "social guilds" as long as you enjoy the people you raid with you'll naturally form a circle. Many the social guilds I've been in only connection is chatting in g-chat which hardly forms the same bonds that spending a few hours together 3-4 days a week tends to.

@jealouspirate
I was spreading this before, but I think I was wrong about the "cross-server" part. I thought that, given the fact a character can freely and easily travel to any server, the guilds would be cross-server.

It was recently revealed that, in GW2, each account will have a "home server", and only be able to fight for that server in the WvWvW (World PvP) battles (although characters should still be able to easily, quickly, and freely visit any server they want, and do any PvE content there). This server limitation seems to point that a player can only be part of guilds in a single server, though I haven't seen specific details yet.

The bit about players being able to be a part of as many guilds as they want is true and confirmed, though. Also, GW2 seems to be aiming at having more players per server than WoW, and also won't have factions dividing server populations into smaller communitites, so it should be way easier to find one or more nice, focused guilds that match with what the player wants to do.