I'm not huge on organized tours, but about 5 years ago we did a Vatican tour with LivItaly:

http://www.livitaly.com/tours/?fwp_c...y=vatican-city

It was the small group vatican and sistine chapel tour. We got lucky and it ended up being just us. We worked with Angelo to book, he's the owner of the company. Our guide I believe was Treva, but it was long enough ago that who knows if she's still working with them.

The tour itself was great. Good pace, lots of information, but again it's been a while for me.