Man I love Avenue Q! I was a bit dubious at first, not guna lie, but it was one of the funniest shows I have ever seen. Such a good fun! Plus like you said the fact that its a parody of sesame street makes it even better. We read quite a few mixed reviews about it before we went but I loved it!
I travel to London to go and see musicals quite a lot as my brother lives there so I try and take the opportunity to have a free personal tour guide as much as I can! Plus he normally sorts me out with an apartment in London for the weekend so I can't really complain!