Vegas casinos boast some good mid-range burger joints, BLT Burger, Le Burger Brassiere (at Paris hotel), and of course the Burger Bar at Mandalay. I wish I could differentiate between the three, but they are all quality eats IMO and worth checking out.
BLT Burger is located w/in Mirage next to a busy walkway and often doesn't have big lines or a wait due to the neighboring food joints. All I've ever had here is the #2. Forget the name, but its the blue cheese and caramelized onion burger... with of course bacon added. Always cooked to perfection. Dripping in juice of course.
What's keeping this from a 5-star place is that I've never been thrilled with the fries or onion rings. I also wish there were sweet potato fries (ala Burger Bar) but all in all, minor complaints here. Service is attentive and good. Central location. Reasonably priced of course. Worth checking out especially if you're in the neighborhood.