IMO Public House (Venetian) is the best place on the strip. They get some of the big name California breweries there that we don't here in DFW (e.g. Bruery). It's a reasonably small set of taps but they keep a diverse range available along with a moderate amount of bottles. They also do cask beers so that's a plus. The Pub in Monte Carlo has a broader selection but not quite as exotic. Those are my two preferred places to hit but many of the hotels, especially the newer ones around City Center, are putting in beer bars. Burger Bar in Mandalay Bay isn't too bad and the food is good. The place in Wynn is supposed to be decent. There are some places to go off the strip but I never make it that far.
I'm not a huge fan of the local breweries although Sin City makes a pretty good hefe and sometimes they run pitcher specials (with a pitcher being about two liters) that tends to be the best deal on beer in town minus the free drinks in the casinos.