Very cool place. Went there on a Monday night with my fiancee based on the recommendation from a friend who said it was a fun place that a lot of locals go to (we wanted a break from the touristy stuff). I almost turned around approaching the door as the place looked seedy as hell from the outside thanks to the presence of two grisly looking bouncers and a nondescript looking entrance. Thankfully we decided to try it out and once you walk through the curtains you're treated to a very cosy fireplace-laden cave with a long bar and a nice social vibe.
The clientele was varied and the service was warm and friendly, both aspects I like when I come into a bar for the first time. Drink prices were a lot more reasonable then the gouging I usually take on the strip, so kudos to them for being real. I think it was in the ballpark of $5-6 for a mixed drink, but can't remember entirely as this was at the tail end of a long night. The fireplaces (surrounded by bench seating) are what I remember best because it was frigid outside (twenty some degrees, record low for that day). And here I thought I was going to get a break from cold weather after leaving Wisconsin. Music was mostly alternative rock, but they mixed it up a bit and it was very agreeable for such a chill place.
They had a backroom which they said has some kind of dubstep mania on Wednesday nights, I was curious but I saw mixed reviews here on Yelp so not really sure what's in store there. I'm not really a dubstep guy but I like a good people-watch every once in a while.
Overall, The Griffin is pretty sweet, I'd advise you stop in after winning that chicken dinner.