Mandalay Bay Burger Bar
I was there this last week and found it to a great spot to catch a game. They have a great list of beers on tap which was the first bonus but I thought the combinations of everything that you can get on the burgers was tasty and fun.
I have read on the boards about others that didnt enjoy but I thought it was great. The topping options are plentiful, albeit the overall price isnt cheap- but this seemed to be a real fun place.