I've been wanting to watch Avenue Q probably since I first heard about it. I still haven't. I was in London last February but didn't have the chance to go to the theatre since I was there for a conference.
The show was meant to close at the end of this year; however, I've just seen their website and discovered that it's been extended until January 2010, which, until now, gives me one month's more chance to get over to London and watch it!
I also really want to watch Wicked but since Avenue Q is likely to close sooner then I'll make a bee-line to the Gielgud Theatre first. Not that I have any plans to go to London, but we'll see - not an impossibility!