Say you started a thread that asked a really good question. Not a question for debate, but a question that you want answered. When you get the answer that's right on the mark, and you're able to use it, you're never going to view the thread again, right? It would kind of defeat the point of leaving it open. I'd like to suggest to PC (or vBulletin, if that's a problem for them to handle) to let everybody close threads, but only (and only) those they started. So if Joe started a thread, and Bob started another thread, Joe could close his thread but not Bob's, and vice versa. That way mods would have more time to actually moderate and be able to spend less time closing threads because people couldn't close their own and they had to say "@mods: please close this now" (something I have done in the past many times). I think this would be a good idea.
Thank you for responses, should you decide to post one.