Bad News: O'Sheas will cease operations in April of 2012 so they can demolish it and the buildings around it as part of the Linq project: http://latimesblogs.latimes.com/nationnow/2011/08/las-vegas-casino-caesars-osheas-linq.html I was in Vegas in March 2012 and it was indeed close to death; they were already destroying the back half of the building and the inside wasn't going to be there much longer.
In theory a new O'Sheas-like venue will be created, but we all know how that goes....
You'll find O'Sheas on the strip across from Caesars, next door to Margaritaville, nearly dead center of the strip. Actually it's probably gone by now, but I'm going to leave this article here for posterity because O'Sheas was one of the classics.
O'Sheas is a really fun casino; it's the only place on the strip that ALWAYS has $5 craps. Their craps tables are pretty huge, so you could be at a table with 20 other people. The drinks come fast and strong at O'Sheas so it can turn into a wild time and get a little rowdy, but if you like that kind of thing (like me), you won't be disappointed.
Further back in the casino, they have plenty of $5 blackjack tables and other various games. In the rear, there are some fast food restaurants along with beer pong tables, where they have casual and organized competitions. It's a blast watching the serious beer pong competitions.