Lawry's Las Vegas offers the excellent prime rib you'd expect from a Lawry's! That said, it's not much of a Vegas-y experience--the restaurant is off-strip and the crowd pretty staid. But if you're there for the quality of the food, not the glitz and glamour, then you'll be happy.
Definitely make a reservation just in case (and there's a private room in the back if you have a large group), and be prepared for the waitstaff to be a little slow (though very friendly).