I have gone to Yassou Greek Grill twice now for lunch and both times it has been a top notch experience. First off their prices appeal to a heeb like me. You can get a huge gyro platter for under $10 bucks, it filled me up both times I have had it. You would be paying $15 or more at another Greek restaurant for a similar dish.
The title of Best Greek food I have had in Las Vegas is a toss up between Market Fresh Grille and Yassou Greek Grill Cafe. Both have been consistently high in quality and taste of the food. The variety of food on the menus will keep you going back for more. But the tie goes to Yassou because of the excellent economical pricing.