This is a difficult question to answer, because just about every artist(s) has performed there. Which means that you could see just about everyone that you like at almost any given time in Las Vegas.
There are so many groups and artists that I would just love to see live in concert in Las Vegas ( or anywhere for that matter) that it is almost confusing.
If I were planning a trip to Las Vegas in the near future, I would most likely find myself the best deal possible on of course the airfare, hotel and find a show that I am wanting to see before headed out.
I don't think you can really experience Las Vegas until you see at least one show of your choice there. Everyone goes there for the gambling fun, but there is just so much more to Las Vegas that it can make your head spin.