Kilroy's has been my favorite burger place since forever, and I've been to plenty of them. I've lived in Vegas for about 15 years now and have still not found a burger place here that's better than Kilroy's. They were voted #1 in the Review Journal and they deserved it!
Kilroy's is a restaurant and gaming bar. The restaurant is separated from the bar which I love (and which is also necessary here, legally). The restaurant is very casual and decorated with movie posters; each one cleverly has Kilroy snuck in the background. The servers are always friendly and quick and the service is great.
Other than burgers, the menu lists sandwiches, chicken fingers, and salads. I always get a burger. My favorite burgers there are the sourdough, the mushroom, and the jalapeno bacon burger. To top it off, I usually get a side of beer-battered fries. Their portions are huge and always good for two people.
For such a casual ho-hum place, Kilroy's is like the royalty of burgers.