I never have any trouble finding great beer to drink in Vegas.
Aces & Ales on Tenaya has 50 beers on tap and 150 different bottle beers, and not one of them is a Bud Miller or Coors.
From the Freakin Frog Website:
Las Vegas' 1st Craft Beer Bar and the largest beer bar in America with almost 1,200 selections. The Freakin' Frog hosts Wooden Cask Events every month and is the proud home of the largest whisky collection in the country.
Rí Rá at Mandalay Bay is a pub that was built in Ireland years ago then disassembled, shipped to Las Vegas and reassembled.
Hofbräuhaus is a faithful reproduction of the centuries-old beer hall in Munich.
The Pub at Monte Carlo has over 300 beers.
The Yardhouse at Red Rock Casino has hundreds of beers.