I normally research a place to the extreme prior to visiting, but I made it a point not to do that with Vegas or Arizona and instead am relying a little on those that I am staying with who know these places almost as well as I know London :).
I have just two places I definitely want to visit, the obvious one being Vegas and the other the Grand Canyon. So as I prepare to take my 10 hour long flight, I have no guide book to absorb on the way and little more than a feeling that this is going to be an amazing experience!
Hope you're enjoying your vacation!! Vegas must be a really cool experience between the holidays.