I'd also heard that "O" was the best from a lot of people who went last year... we really want to hit a show while we're in town again this time - so we've been looking around too.
A great site for anyone wanting to see a full listing of all that's there is
http://www.vegas.com
You can search by your arrival dates, what type of show you'd like to see, etc. - even pricing. They list all show dates, reveal black out dates, etc. and give full pricing and contact info for ordering tickets.
A really helpful site.
