Just got back from Vegas a few weeks ago. We loved The Pub at Monte Carlo. Great selection cool place and good location because we stayed at Aria. It is all the way in the back of the resort by the shops.
I actually really liked Ellis Island. They've got a pretty good stout. All of their beers come in a frosted glass, so you may want to let it sit for a while. Also, be sure to try the breakfast burrito! It is amazing!