Yama is a great off the strip place to visit for lunch. We normally drop in on our way up from the valley. I really like to sit at the sushi bar and banter with the chefs as they make whatever you like. The quality for the price is great, very nice white tuna, great mackerel - It isn't fine dining or what have you but the quality is there.
I enjoy the seafood salad that they make and my better half likes some of their baked rolls.
They make one thing in particular that is out of this world, to me at least. Hamachi Kama is so good there. Not fried, just grilled like you don't want to know. One thing to note is that it gets really busy, really fast so sitting at the sushi bar as a couple is great.
Since May, they expanded and have a U shaped sushi bar and much more seating so it might be a bit better for wait times. It is all you can eat if you want it, and well worth it.