I stayed in the same guild for the entirety of Vanilla and BC. I left it a month~ before WotLK hit because of changes within the leadership and the guild changing directions. It didn't really 'die', but it went from being somewhat competitive and at least clearing all content to being a casual guild which wasn't for me. That guild still existed back in Cata, I haven't followed if they keep raiding casually in MoP but I do have fond memories of that time.
In WotLK I joined a new guild but left at some point during Ulduar because the guys in there were just pricks. Said guild died a few months later during ToGC. My only awful guild experience in this game.
Took a break til Cata by doing deluxe pugs and shit
Joined a new guild in Cata, stayed in it til we parted ways after we killed Madness. The guild didn't die because of tensions or anything of the sort, but most people simply didn't care about the game anymore, so we had a debate whether to do Dragon Soul or not, and agreed to quit raiding after Madness would die and give Dragon Soul everything we had, finished with a very nice ranking on Madness. Everyone then went their own way. We still hang around in our mumble a lot.
Joined my current guild right after that, will probably stay until they can't put up with me anymore!