We're not a big Guild. All told, we probably have about twenty to twenty five people who come online at various times to talk, chat, and play together. We have some structure, but we're mostly a motley of friends who hang out. Our raiding effort takes place because our raid leaders woke up one day and said "By Wrath of the Lich King, we're going to be able to progress in ten man content."
We're also a roleplay-ish kind of Guild. I say "ish" because we're not full immersion players. We have some light story notions. For example, I have the vague idea that our raid's main healer is the son of our raid's main tank -- that's mostly because they're the same human model, but one has light blonde hair, and the other has old, graying hair.
So, when we come across folks into the roleplay and immersion a little more than we are, we're sometimes not quite sure what to make of it.